diff --git a/artiq/compiler/builtins.py b/artiq/compiler/builtins.py
index baef12797..77703ed3c 100644
--- a/artiq/compiler/builtins.py
+++ b/artiq/compiler/builtins.py
@@ -44,6 +44,13 @@ def TInt32():
 def TInt64():
     return TInt(types.TValue(64))
 
+def _int_printer(typ, depth, max_depth):
+    if types.is_var(typ["width"]):
+        return "numpy.int?"
+    else:
+        return "numpy.int{}".format(types.get_value(typ.find()["width"]))
+types.TypePrinter.custom_printers['int'] = _int_printer
+
 class TFloat(types.TMono):
     def __init__(self):
         super().__init__("float")
@@ -83,7 +90,7 @@ class TException(types.TMono):
     #    (which also serves as the EHABI type_info).
     #  * File, line and column where it was raised (str, int, int).
     #  * Message, which can contain substitutions {0}, {1} and {2} (str).
-    #  * Three 64-bit integers, parameterizing the message (int(width=64)).
+    #  * Three 64-bit integers, parameterizing the message (numpy.int64).
 
     # Keep this in sync with the function ARTIQIRGenerator.alloc_exn.
     attributes = OrderedDict([
diff --git a/artiq/compiler/transforms/inferencer.py b/artiq/compiler/transforms/inferencer.py
index 59d215c84..56eeeb9a0 100644
--- a/artiq/compiler/transforms/inferencer.py
+++ b/artiq/compiler/transforms/inferencer.py
@@ -579,11 +579,11 @@ class Inferencer(algorithm.Visitor):
             valid_forms = lambda: [
                 valid_form("{exn}() -> {exn}".format(exn=typ.name)),
                 valid_form("{exn}(message:str) -> {exn}".format(exn=typ.name)),
-                valid_form("{exn}(message:str, param1:int(width=64)) -> {exn}".format(exn=typ.name)),
-                valid_form("{exn}(message:str, param1:int(width=64), "
-                           "param2:int(width=64)) -> {exn}".format(exn=typ.name)),
-                valid_form("{exn}(message:str, param1:int(width=64), "
-                           "param2:int(width=64), param3:int(width=64)) "
+                valid_form("{exn}(message:str, param1:numpy.int64) -> {exn}".format(exn=typ.name)),
+                valid_form("{exn}(message:str, param1:numpy.int64, "
+                           "param2:numpy.int64) -> {exn}".format(exn=typ.name)),
+                valid_form("{exn}(message:str, param1:numpy.int64, "
+                           "param2:numpy.int64, param3:numpy.int64) "
                            "-> {exn}".format(exn=typ.name)),
             ]
 
@@ -858,19 +858,19 @@ class Inferencer(algorithm.Visitor):
             simple_form("at(time:float) -> None",
                         [builtins.TFloat()])
         elif types.is_builtin(typ, "now_mu"):
-            simple_form("now_mu() -> int(width=64)",
+            simple_form("now_mu() -> numpy.int64",
                         [], builtins.TInt64())
         elif types.is_builtin(typ, "delay_mu"):
-            simple_form("delay_mu(time_mu:int(width=64)) -> None",
+            simple_form("delay_mu(time_mu:numpy.int64) -> None",
                         [builtins.TInt64()])
         elif types.is_builtin(typ, "at_mu"):
-            simple_form("at_mu(time_mu:int(width=64)) -> None",
+            simple_form("at_mu(time_mu:numpy.int64) -> None",
                         [builtins.TInt64()])
         elif types.is_builtin(typ, "mu_to_seconds"):
-            simple_form("mu_to_seconds(time_mu:int(width=64)) -> float",
+            simple_form("mu_to_seconds(time_mu:numpy.int64) -> float",
                         [builtins.TInt64()], builtins.TFloat())
         elif types.is_builtin(typ, "seconds_to_mu"):
-            simple_form("seconds_to_mu(time:float) -> int(width=64)",
+            simple_form("seconds_to_mu(time:float) -> numpy.int64",
                         [builtins.TFloat()], builtins.TInt64())
         elif types.is_builtin(typ, "watchdog"):
             simple_form("watchdog(time:float) -> [builtin context manager]",
diff --git a/artiq/compiler/types.py b/artiq/compiler/types.py
index ac1e9377c..04ba46f75 100644
--- a/artiq/compiler/types.py
+++ b/artiq/compiler/types.py
@@ -670,6 +670,8 @@ class TypePrinter(object):
     type variables sequential alphabetic names.
     """
 
+    custom_printers = {}
+
     def __init__(self):
         self.gen = genalnum()
         self.map = {}
@@ -694,7 +696,9 @@ class TypePrinter(object):
                 self.recurse_guard.add(typ)
                 return "<instance {} {{}}>".format(typ.name)
         elif isinstance(typ, TMono):
-            if typ.params == {}:
+            if typ.name in self.custom_printers:
+                return self.custom_printers[typ.name](typ, depth + 1, max_depth)
+            elif typ.params == {}:
                 return typ.name
             else:
                 return "%s(%s)" % (typ.name, ", ".join(
diff --git a/artiq/test/lit/embedding/error_attr_conflict.py b/artiq/test/lit/embedding/error_attr_conflict.py
index e38d45fba..a8556dd2c 100644
--- a/artiq/test/lit/embedding/error_attr_conflict.py
+++ b/artiq/test/lit/embedding/error_attr_conflict.py
@@ -15,7 +15,7 @@ i2.x = 1.0
 
 @kernel
 def entrypoint():
-    # CHECK-L: <synthesized>:1: error: host object has an attribute 'x' of type float, which is different from previously inferred type int(width=32) for the same attribute
+    # CHECK-L: <synthesized>:1: error: host object has an attribute 'x' of type float, which is different from previously inferred type numpy.int32 for the same attribute
     i1.x
     # CHECK-L: ${LINE:+1}: note: expanded from here
     i2.x
diff --git a/artiq/test/lit/embedding/error_attr_unify.py b/artiq/test/lit/embedding/error_attr_unify.py
index b677d2822..c8f6321a8 100644
--- a/artiq/test/lit/embedding/error_attr_unify.py
+++ b/artiq/test/lit/embedding/error_attr_unify.py
@@ -9,7 +9,7 @@ class c:
 
 @kernel
 def entrypoint():
-    # CHECK-L: <synthesized>:1: error: cannot unify int(width='a) with str
+    # CHECK-L: <synthesized>:1: error: cannot unify numpy.int? with str
     # CHECK-NEXT-L: [1, 'x']
     # CHECK-L: ${LINE:+1}: note: expanded from here
     a = c
diff --git a/artiq/test/lit/inferencer/builtin_calls.py b/artiq/test/lit/inferencer/builtin_calls.py
index 1b3157e2e..c461d5a03 100644
--- a/artiq/test/lit/inferencer/builtin_calls.py
+++ b/artiq/test/lit/inferencer/builtin_calls.py
@@ -7,29 +7,29 @@ bool()
 # CHECK-L: bool:<constructor bool>([]:list(elt='a)):bool
 bool([])
 
-# CHECK-L: int:<constructor int {}>():int(width='b)
+# CHECK-L: int:<constructor int {}>():numpy.int?
 int()
 
-# CHECK-L: int:<constructor int>(1.0:float):int(width='c)
+# CHECK-L: int:<constructor int>(1.0:float):numpy.int?
 int(1.0)
 
-# CHECK-L: int:<constructor int>(1.0:float, width=64:int(width='d)):int(width=64)
+# CHECK-L: int:<constructor int>(1.0:float, width=64:numpy.int?):numpy.int64
 int(1.0, width=64)
 
 # CHECK-L: float:<constructor float {}>():float
 float()
 
-# CHECK-L: float:<constructor float>(1:int(width='e)):float
+# CHECK-L: float:<constructor float>(1:numpy.int?):float
 float(1)
 
-# CHECK-L: list:<constructor list {}>():list(elt='f)
+# CHECK-L: list:<constructor list {}>():list(elt='b)
 list()
 
-# CHECK-L: len:<function len>([]:list(elt='g)):int(width=32)
+# CHECK-L: len:<function len>([]:list(elt='c)):numpy.int32
 len([])
 
-# CHECK-L: round:<function round>(1.0:float):int(width='h)
+# CHECK-L: round:<function round>(1.0:float):numpy.int?
 round(1.0)
 
-# CHECK-L: round:<function round>(1.0:float, width=64:int(width='i)):int(width=64)
+# CHECK-L: round:<function round>(1.0:float, width=64:numpy.int?):numpy.int64
 round(1.0, width=64)
diff --git a/artiq/test/lit/inferencer/class.py b/artiq/test/lit/inferencer/class.py
index 1249474a0..4e26b7c58 100644
--- a/artiq/test/lit/inferencer/class.py
+++ b/artiq/test/lit/inferencer/class.py
@@ -8,12 +8,12 @@ class c:
     def m(self):
         pass
 
-# CHECK-L: c:<constructor c {a: int(width='a), f: ()->NoneType delay('b), m: (self:<instance c>)->NoneType delay('c)}>
+# CHECK-L: c:<constructor c {a: numpy.int?, f: ()->NoneType delay('a), m: (self:<instance c>)->NoneType delay('b)}>
 c
-# CHECK-L: .a:int(width='a)
+# CHECK-L: .a:numpy.int?
 c.a
-# CHECK-L: .f:()->NoneType delay('b)
+# CHECK-L: .f:()->NoneType delay('a)
 c.f
 
-# CHECK-L: .m:method(fn=(self:<instance c>)->NoneType delay('c), self=<instance c>)
+# CHECK-L: .m:method(fn=(self:<instance c>)->NoneType delay('b), self=<instance c>)
 c().m()
diff --git a/artiq/test/lit/inferencer/coerce.py b/artiq/test/lit/inferencer/coerce.py
index 04fe42bbc..714bf6ad0 100644
--- a/artiq/test/lit/inferencer/coerce.py
+++ b/artiq/test/lit/inferencer/coerce.py
@@ -2,40 +2,40 @@
 # RUN: OutputCheck %s --file-to-check=%t
 
 1 | 2
-# CHECK-L: 1:int(width='a):int(width='b) | 2:int(width='c):int(width='b):int(width='b)
+# CHECK-L: 1:numpy.int?:numpy.int? | 2:numpy.int?:numpy.int?:numpy.int?
 
 1 + 2
-# CHECK-L: 1:int(width='d):int(width='e) + 2:int(width='f):int(width='e):int(width='e)
+# CHECK-L: 1:numpy.int?:numpy.int? + 2:numpy.int?:numpy.int?:numpy.int?
 
 (1,) + (2.0,)
-# CHECK-L: (1:int(width='g),):(int(width='g),) + (2.0:float,):(float,):(int(width='g), float)
+# CHECK-L: (1:numpy.int?,):(numpy.int?,) + (2.0:float,):(float,):(numpy.int?, float)
 
 [1] + [2]
-# CHECK-L: [1:int(width='h)]:list(elt=int(width='h)) + [2:int(width='h)]:list(elt=int(width='h)):list(elt=int(width='h))
+# CHECK-L: [1:numpy.int?]:list(elt=numpy.int?) + [2:numpy.int?]:list(elt=numpy.int?):list(elt=numpy.int?)
 
 1 * 2
-# CHECK-L: 1:int(width='i):int(width='j) * 2:int(width='k):int(width='j):int(width='j)
+# CHECK-L: 1:numpy.int?:numpy.int? * 2:numpy.int?:numpy.int?:numpy.int?
 
 [1] * 2
-# CHECK-L: [1:int(width='l)]:list(elt=int(width='l)) * 2:int(width='m):list(elt=int(width='l))
+# CHECK-L: [1:numpy.int?]:list(elt=numpy.int?) * 2:numpy.int?:list(elt=numpy.int?)
 
 1 // 2
-# CHECK-L: 1:int(width='n):int(width='o) // 2:int(width='p):int(width='o):int(width='o)
+# CHECK-L: 1:numpy.int?:numpy.int? // 2:numpy.int?:numpy.int?:numpy.int?
 
 1 + 1.0
-# CHECK-L: 1:int(width='q):float + 1.0:float:float
+# CHECK-L: 1:numpy.int?:float + 1.0:float:float
 
 a = []; a += [1]
-# CHECK-L: a:list(elt=int(width='r)) = []:list(elt=int(width='r)); a:list(elt=int(width='r)) += [1:int(width='r)]:list(elt=int(width='r))
+# CHECK-L: a:list(elt=numpy.int?) = []:list(elt=numpy.int?); a:list(elt=numpy.int?) += [1:numpy.int?]:list(elt=numpy.int?)
 
 [] is [1]
-# CHECK-L: []:list(elt=int(width='s)) is [1:int(width='s)]:list(elt=int(width='s)):bool
+# CHECK-L: []:list(elt=numpy.int?) is [1:numpy.int?]:list(elt=numpy.int?):bool
 
 1 in [1]
-# CHECK-L: 1:int(width='t) in [1:int(width='t)]:list(elt=int(width='t)):bool
+# CHECK-L: 1:numpy.int? in [1:numpy.int?]:list(elt=numpy.int?):bool
 
 [] < [1]
-# CHECK-L: []:list(elt=int(width='u)) < [1:int(width='u)]:list(elt=int(width='u)):bool
+# CHECK-L: []:list(elt=numpy.int?) < [1:numpy.int?]:list(elt=numpy.int?):bool
 
 1.0 < 1
-# CHECK-L: 1.0:float < 1:int(width='v):float:bool
+# CHECK-L: 1.0:float < 1:numpy.int?:float:bool
diff --git a/artiq/test/lit/inferencer/error_call.py b/artiq/test/lit/inferencer/error_call.py
index 739ffa249..1c3df3a6a 100644
--- a/artiq/test/lit/inferencer/error_call.py
+++ b/artiq/test/lit/inferencer/error_call.py
@@ -1,7 +1,7 @@
 # RUN: %python -m artiq.compiler.testbench.inferencer +diag %s >%t
 # RUN: OutputCheck %s --file-to-check=%t
 
-# CHECK-L: ${LINE:+1}: error: cannot call this expression of type int
+# CHECK-L: ${LINE:+1}: error: cannot call this expression of type numpy.int?
 (1)()
 
 def f(x, y, z=1):
diff --git a/artiq/test/lit/inferencer/error_coerce.py b/artiq/test/lit/inferencer/error_coerce.py
index bf4a5dd36..8afb83e6b 100644
--- a/artiq/test/lit/inferencer/error_coerce.py
+++ b/artiq/test/lit/inferencer/error_coerce.py
@@ -5,33 +5,33 @@
 1 << 2.0
 
 # CHECK-L: ${LINE:+3}: error: expected every '+' operand to be a list in this context
-# CHECK-L: ${LINE:+2}: note: list of type list(elt=int(width='a))
-# CHECK-L: ${LINE:+1}: note: int(width='b), which cannot be added to a list
+# CHECK-L: ${LINE:+2}: note: list of type list(elt=numpy.int?)
+# CHECK-L: ${LINE:+1}: note: numpy.int?, which cannot be added to a list
 [1] + 2
 
-# CHECK-L: ${LINE:+1}: error: cannot unify list(elt=int(width='a)) with list(elt=float): int(width='a) is incompatible with float
+# CHECK-L: ${LINE:+1}: error: cannot unify list(elt=numpy.int?) with list(elt=float): numpy.int? is incompatible with float
 [1] + [2.0]
 
 # CHECK-L: ${LINE:+3}: error: expected every '+' operand to be a tuple in this context
-# CHECK-L: ${LINE:+2}: note: tuple of type (int(width='a),)
-# CHECK-L: ${LINE:+1}: note: int(width='b), which cannot be added to a tuple
+# CHECK-L: ${LINE:+2}: note: tuple of type (numpy.int?,)
+# CHECK-L: ${LINE:+1}: note: numpy.int?, which cannot be added to a tuple
 (1,) + 2
 
 # CHECK-L: ${LINE:+1}: error: passing tuples to '*' is not supported
 (1,) * 2
 
 # CHECK-L: ${LINE:+3}: error: expected '*' operands to be a list and an integer in this context
-# CHECK-L: ${LINE:+2}: note: list operand of type list(elt=int(width='a))
-# CHECK-L: ${LINE:+1}: note: operand of type list(elt='b), which is not a valid repetition amount
+# CHECK-L: ${LINE:+2}: note: list operand of type list(elt=numpy.int?)
+# CHECK-L: ${LINE:+1}: note: operand of type list(elt='a), which is not a valid repetition amount
 [1] * []
 
 # CHECK-L: ${LINE:+1}: error: cannot coerce list(elt='a) to a numeric type
 [] - 1.0
 
-# CHECK-L: ${LINE:+2}: error: expression of type int(width='a) has to be coerced to float, which makes assignment invalid
+# CHECK-L: ${LINE:+2}: error: expression of type numpy.int? has to be coerced to float, which makes assignment invalid
 # CHECK-L: ${LINE:+1}: note: expression of type float
 a = 1; a += 1.0
 
-# CHECK-L: ${LINE:+2}: error: the result of this operation has type (int(width='a), float), which makes assignment to a slot of type (int(width='a),) invalid
+# CHECK-L: ${LINE:+2}: error: the result of this operation has type (numpy.int?, float), which makes assignment to a slot of type (numpy.int?,) invalid
 # CHECK-L: ${LINE:+1}: note: expression of type (float,)
 b = (1,); b += (1.0,)
diff --git a/artiq/test/lit/inferencer/error_exception.py b/artiq/test/lit/inferencer/error_exception.py
index 4e4b340b5..ee049bb2a 100644
--- a/artiq/test/lit/inferencer/error_exception.py
+++ b/artiq/test/lit/inferencer/error_exception.py
@@ -9,6 +9,6 @@ except 1:
 
 try:
     pass
-# CHECK-L: ${LINE:+1}: error: cannot unify int(width='a) with Exception
+# CHECK-L: ${LINE:+1}: error: cannot unify numpy.int? with Exception
 except Exception as e:
     e = 1
diff --git a/artiq/test/lit/inferencer/error_iterable.py b/artiq/test/lit/inferencer/error_iterable.py
index 68ed1b002..73afa2fcc 100644
--- a/artiq/test/lit/inferencer/error_iterable.py
+++ b/artiq/test/lit/inferencer/error_iterable.py
@@ -1,5 +1,5 @@
 # RUN: %python -m artiq.compiler.testbench.inferencer +diag %s >%t
 # RUN: OutputCheck %s --file-to-check=%t
 
-# CHECK-L: ${LINE:+1}: error: type int(width='a) is not iterable
+# CHECK-L: ${LINE:+1}: error: type numpy.int? is not iterable
 for x in 1: pass
diff --git a/artiq/test/lit/inferencer/error_method.py b/artiq/test/lit/inferencer/error_method.py
index cb4f77075..2f4d1d3fe 100644
--- a/artiq/test/lit/inferencer/error_method.py
+++ b/artiq/test/lit/inferencer/error_method.py
@@ -12,5 +12,5 @@ class c:
 c().f()
 
 c.g(1)
-# CHECK-L: ${LINE:+1}: error: cannot unify <instance c> with int(width='a) while inferring the type for self argument
+# CHECK-L: ${LINE:+1}: error: cannot unify <instance c> with numpy.int? while inferring the type for self argument
 c().g()
diff --git a/artiq/test/lit/inferencer/error_return.py b/artiq/test/lit/inferencer/error_return.py
index ba4ddc2b3..40e6fd889 100644
--- a/artiq/test/lit/inferencer/error_return.py
+++ b/artiq/test/lit/inferencer/error_return.py
@@ -1,16 +1,16 @@
 # RUN: %python -m artiq.compiler.testbench.inferencer +diag %s >%t
 # RUN: OutputCheck %s --file-to-check=%t
 
-# CHECK-L: ${LINE:+2}: error: cannot unify int(width='a) with NoneType
-# CHECK-L: ${LINE:+1}: note: function with return type int(width='a)
+# CHECK-L: ${LINE:+2}: error: cannot unify numpy.int? with NoneType
+# CHECK-L: ${LINE:+1}: note: function with return type numpy.int?
 def a():
     return 1
     # CHECK-L: ${LINE:+1}: note: a statement returning NoneType
     return
 
-# CHECK-L: ${LINE:+2}: error: cannot unify int(width='a) with list(elt='b)
-# CHECK-L: ${LINE:+1}: note: function with return type int(width='a)
+# CHECK-L: ${LINE:+2}: error: cannot unify numpy.int? with list(elt='a)
+# CHECK-L: ${LINE:+1}: note: function with return type numpy.int?
 def b():
     return 1
-    # CHECK-L: ${LINE:+1}: note: a statement returning list(elt='b)
+    # CHECK-L: ${LINE:+1}: note: a statement returning list(elt='a)
     return []
diff --git a/artiq/test/lit/inferencer/error_unify.py b/artiq/test/lit/inferencer/error_unify.py
index e81537d29..636d4f85a 100644
--- a/artiq/test/lit/inferencer/error_unify.py
+++ b/artiq/test/lit/inferencer/error_unify.py
@@ -4,17 +4,17 @@
 a = 1
 b = []
 
-# CHECK-L: ${LINE:+1}: error: cannot unify int(width='a) with list(elt='b)
+# CHECK-L: ${LINE:+1}: error: cannot unify numpy.int? with list(elt='a)
 a = b
 
-# CHECK-L: ${LINE:+1}: error: cannot unify int(width='a) with list(elt='b)
+# CHECK-L: ${LINE:+1}: error: cannot unify numpy.int? with list(elt='a)
 [1, []]
-# CHECK-L: note: a list element of type int(width='a)
-# CHECK-L: note: a list element of type list(elt='b)
+# CHECK-L: note: a list element of type numpy.int?
+# CHECK-L: note: a list element of type list(elt='a)
 
-# CHECK-L: ${LINE:+1}: error: cannot unify int(width='a) with bool
+# CHECK-L: ${LINE:+1}: error: cannot unify numpy.int? with bool
 1 and False
-# CHECK-L: note: an operand of type int(width='a)
+# CHECK-L: note: an operand of type numpy.int?
 # CHECK-L: note: an operand of type bool
 
 # CHECK-L: ${LINE:+1}: error: expected unary '+' operand to be of numeric type, not list(elt='a)
@@ -23,5 +23,5 @@ a = b
 # CHECK-L: ${LINE:+1}: error: expected '~' operand to be of integer type, not float
 ~1.0
 
-# CHECK-L: ${LINE:+1}: error: type int(width='a) does not have an attribute 'x'
+# CHECK-L: ${LINE:+1}: error: type numpy.int? does not have an attribute 'x'
 (1).x
diff --git a/artiq/test/lit/inferencer/error_with_exn.py b/artiq/test/lit/inferencer/error_with_exn.py
index 27d6b1b54..283dadb5a 100644
--- a/artiq/test/lit/inferencer/error_with_exn.py
+++ b/artiq/test/lit/inferencer/error_with_exn.py
@@ -10,7 +10,7 @@ class contextmgr:
         pass
 
 def foo():
-    # CHECK-L: ${LINE:+2}: error: cannot unify int(width='a) with NoneType
-    # CHECK-L: ${LINE:+1}: note: exception handling via context managers is not supported; the argument 'n3' of function '__exit__(self:<instance contextmgr>, n1:NoneType, n2:NoneType, n3:int(width='a))->NoneType delay('b)' will always be None
+    # CHECK-L: ${LINE:+2}: error: cannot unify numpy.int? with NoneType
+    # CHECK-L: ${LINE:+1}: note: exception handling via context managers is not supported; the argument 'n3' of function '__exit__(self:<instance contextmgr>, n1:NoneType, n2:NoneType, n3:numpy.int?)->NoneType delay('a)' will always be None
     with contextmgr():
         pass
diff --git a/artiq/test/lit/inferencer/error_with_self.py b/artiq/test/lit/inferencer/error_with_self.py
index afe53e531..d22c5c085 100644
--- a/artiq/test/lit/inferencer/error_with_self.py
+++ b/artiq/test/lit/inferencer/error_with_self.py
@@ -10,8 +10,8 @@ class contextmgr:
 
 def foo():
     contextmgr.__enter__(1)
-    # CHECK-L: ${LINE:+3}: error: cannot unify <instance contextmgr> with int(width='a) while inferring the type for self argument
+    # CHECK-L: ${LINE:+3}: error: cannot unify <instance contextmgr> with numpy.int? while inferring the type for self argument
     # CHECK-L: ${LINE:+2}: note: expression of type <instance contextmgr {}>
-    # CHECK-L: ${LINE:+1}: note: reference to an instance with a method '__enter__(self:int(width='a))->NoneType delay('b)'
+    # CHECK-L: ${LINE:+1}: note: reference to an instance with a method '__enter__(self:numpy.int?)->NoneType delay('a)'
     with contextmgr():
         pass
diff --git a/artiq/test/lit/inferencer/gcd.py b/artiq/test/lit/inferencer/gcd.py
index e2d4b4779..3137d7cc0 100644
--- a/artiq/test/lit/inferencer/gcd.py
+++ b/artiq/test/lit/inferencer/gcd.py
@@ -9,5 +9,5 @@ def _gcd(a, b):
         b = c
     return b
 
-# CHECK-L: _gcd:(a:int(width='a), b:int(width='a))->int(width='a)(10:int(width='a), 25:int(width='a)):int(width='a)
+# CHECK-L: _gcd:(a:numpy.int?, b:numpy.int?)->numpy.int?(10:numpy.int?, 25:numpy.int?):numpy.int?
 _gcd(10, 25)
diff --git a/artiq/test/lit/inferencer/prelude.py b/artiq/test/lit/inferencer/prelude.py
index 643895e4a..288cc78b3 100644
--- a/artiq/test/lit/inferencer/prelude.py
+++ b/artiq/test/lit/inferencer/prelude.py
@@ -6,5 +6,5 @@ x = len
 
 def f():
     global len
-    # CHECK-L: len:int(width='a) =
+    # CHECK-L: len:numpy.int? =
     len = 1
diff --git a/artiq/test/lit/inferencer/scoping.py b/artiq/test/lit/inferencer/scoping.py
index 604b2425d..9847ef0ea 100644
--- a/artiq/test/lit/inferencer/scoping.py
+++ b/artiq/test/lit/inferencer/scoping.py
@@ -1,7 +1,7 @@
 # RUN: %python -m artiq.compiler.testbench.inferencer %s >%t
 # RUN: OutputCheck %s --file-to-check=%t
 
-# CHECK-L: []:list(elt=int(width='a))
+# CHECK-L: []:list(elt=numpy.int?)
 x = []
 
 def f():
diff --git a/artiq/test/lit/inferencer/slice.py b/artiq/test/lit/inferencer/slice.py
index 1693bcd85..610fa9dc3 100644
--- a/artiq/test/lit/inferencer/slice.py
+++ b/artiq/test/lit/inferencer/slice.py
@@ -2,5 +2,5 @@
 # RUN: OutputCheck %s --file-to-check=%t
 
 x = [0]
-# CHECK-L: [::int(width=32)]
+# CHECK-L: [::numpy.int32]
 x[:] = [1]
diff --git a/artiq/test/lit/inferencer/unify.py b/artiq/test/lit/inferencer/unify.py
index 59d23e937..a0dadaf1e 100644
--- a/artiq/test/lit/inferencer/unify.py
+++ b/artiq/test/lit/inferencer/unify.py
@@ -2,10 +2,10 @@
 # RUN: OutputCheck %s --file-to-check=%t
 
 a = 1
-# CHECK-L: a:int(width='a)
+# CHECK-L: a:numpy.int?
 
 b = a
-# CHECK-L: b:int(width='a)
+# CHECK-L: b:numpy.int?
 
 c = True
 # CHECK-L: c:bool
@@ -20,39 +20,39 @@ f = 1.0
 # CHECK-L: f:float
 
 g = []
-# CHECK-L: g:list(elt='b)
+# CHECK-L: g:list(elt='a)
 
 h = [1]
-# CHECK-L: h:list(elt=int(width='c))
+# CHECK-L: h:list(elt=numpy.int?)
 
 i = []
 i[0] = 1
-# CHECK-L: i:list(elt=int(width='d))
+# CHECK-L: i:list(elt=numpy.int?)
 
 j = []
 j += [1.0]
 # CHECK-L: j:list(elt=float)
 
 1 if a else 2
-# CHECK-L: 1:int(width='f) if a:int(width='a) else 2:int(width='f):int(width='f)
+# CHECK-L: 1:numpy.int? if a:numpy.int? else 2:numpy.int?:numpy.int?
 
 True and False
 # CHECK-L: True:bool and False:bool:bool
 
 1 and 0
-# CHECK-L: 1:int(width='g) and 0:int(width='g):int(width='g)
+# CHECK-L: 1:numpy.int? and 0:numpy.int?:numpy.int?
 
 ~1
-# CHECK-L: 1:int(width='h):int(width='h)
+# CHECK-L: 1:numpy.int?:numpy.int?
 
 not 1
-# CHECK-L: 1:int(width='i):bool
+# CHECK-L: 1:numpy.int?:bool
 
 [x for x in [1]]
-# CHECK-L: [x:int(width='j) for x:int(width='j) in [1:int(width='j)]:list(elt=int(width='j))]:list(elt=int(width='j))
+# CHECK-L: [x:numpy.int? for x:numpy.int? in [1:numpy.int?]:list(elt=numpy.int?)]:list(elt=numpy.int?)
 
 lambda x, y=1: x
-# CHECK-L: lambda x:'k, y:int(width='l)=1:int(width='l): x:'k:(x:'k, ?y:int(width='l))->'k
+# CHECK-L: lambda x:'b, y:numpy.int?=1:numpy.int?: x:'b:(x:'b, ?y:numpy.int?)->'b
 
 k = "x"
 # CHECK-L: k:str
@@ -64,10 +64,10 @@ IndexError("x")
 # CHECK-L: IndexError:<constructor IndexError>("x":str):IndexError
 
 IndexError("x", 1)
-# CHECK-L: IndexError:<constructor IndexError>("x":str, 1:int(width=64)):IndexError
+# CHECK-L: IndexError:<constructor IndexError>("x":str, 1:numpy.int64):IndexError
 
 IndexError("x", 1, 1)
-# CHECK-L: IndexError:<constructor IndexError>("x":str, 1:int(width=64), 1:int(width=64)):IndexError
+# CHECK-L: IndexError:<constructor IndexError>("x":str, 1:numpy.int64, 1:numpy.int64):IndexError
 
 IndexError("x", 1, 1, 1)
-# CHECK-L: IndexError:<constructor IndexError>("x":str, 1:int(width=64), 1:int(width=64), 1:int(width=64)):IndexError
+# CHECK-L: IndexError:<constructor IndexError>("x":str, 1:numpy.int64, 1:numpy.int64, 1:numpy.int64):IndexError
diff --git a/artiq/test/lit/iodelay/argument.py b/artiq/test/lit/iodelay/argument.py
index f026c78f1..94da1c764 100644
--- a/artiq/test/lit/iodelay/argument.py
+++ b/artiq/test/lit/iodelay/argument.py
@@ -1,7 +1,7 @@
 # RUN: %python -m artiq.compiler.testbench.signature %s >%t
 # RUN: OutputCheck %s --file-to-check=%t
 
-# CHECK-L: f: (a:float, b:int(width=64))->NoneType delay(s->mu(a) + b mu)
+# CHECK-L: f: (a:float, b:numpy.int64)->NoneType delay(s->mu(a) + b mu)
 def f(a, b):
     delay(a)
     delay_mu(b)
diff --git a/artiq/test/lit/iodelay/arith.py b/artiq/test/lit/iodelay/arith.py
index 0eba79715..05d42e666 100644
--- a/artiq/test/lit/iodelay/arith.py
+++ b/artiq/test/lit/iodelay/arith.py
@@ -1,7 +1,7 @@
 # RUN: %python -m artiq.compiler.testbench.signature %s >%t
 # RUN: OutputCheck %s --file-to-check=%t
 
-# CHECK-L: f: (a:int(width=32), b:int(width=32), c:int(width=32), d:int(width=32), e:int(width=32))->NoneType delay(s->mu(a * b // c + d - 10 / e) mu)
+# CHECK-L: f: (a:numpy.int32, b:numpy.int32, c:numpy.int32, d:numpy.int32, e:numpy.int32)->NoneType delay(s->mu(a * b // c + d - 10 / e) mu)
 def f(a, b, c, d, e):
     delay(a * b // c + d - 10 / e)
 
diff --git a/artiq/test/lit/iodelay/interleave.py b/artiq/test/lit/iodelay/interleave.py
index 598c572de..76e30b7a7 100644
--- a/artiq/test/lit/iodelay/interleave.py
+++ b/artiq/test/lit/iodelay/interleave.py
@@ -1,13 +1,13 @@
 # RUN: %python -m artiq.compiler.testbench.signature %s >%t
 # RUN: OutputCheck %s --file-to-check=%t
 
-# CHECK-L: f: (a:int(width=64), b:int(width=64))->NoneType delay(max(a, b) mu)
+# CHECK-L: f: (a:numpy.int64, b:numpy.int64)->NoneType delay(max(a, b) mu)
 def f(a, b):
     with interleave:
         delay_mu(a)
         delay_mu(b)
 
-# CHECK-L: g: (a:int(width=64))->NoneType delay(max(a, 200) mu)
+# CHECK-L: g: (a:numpy.int64)->NoneType delay(max(a, 200) mu)
 def g(a):
     with interleave:
         delay_mu(100)
diff --git a/artiq/test/lit/iodelay/range.py b/artiq/test/lit/iodelay/range.py
index 9c4a73a79..c5592927e 100644
--- a/artiq/test/lit/iodelay/range.py
+++ b/artiq/test/lit/iodelay/range.py
@@ -1,17 +1,17 @@
 # RUN: %python -m artiq.compiler.testbench.signature %s >%t
 # RUN: OutputCheck %s --file-to-check=%t
 
-# CHECK-L: f: (a:int(width=32))->NoneType delay(3 * a mu)
+# CHECK-L: f: (a:numpy.int32)->NoneType delay(3 * a mu)
 def f(a):
     for _ in range(a):
         delay_mu(3)
 
-# CHECK-L: g: (a:int(width=32), b:int(width=32))->NoneType delay(3 * (b - a) mu)
+# CHECK-L: g: (a:numpy.int32, b:numpy.int32)->NoneType delay(3 * (b - a) mu)
 def g(a, b):
     for _ in range(a, b):
         delay_mu(3)
 
-# CHECK-L: h: (a:int(width=32), b:int(width=32), c:int(width=32))->NoneType delay(3 * (b - a) // c mu)
+# CHECK-L: h: (a:numpy.int32, b:numpy.int32, c:numpy.int32)->NoneType delay(3 * (b - a) // c mu)
 def h(a, b, c):
     for _ in range(a, b, c):
         delay_mu(3)
diff --git a/artiq/test/lit/iodelay/return.py b/artiq/test/lit/iodelay/return.py
index d07267a44..9eefe1f54 100644
--- a/artiq/test/lit/iodelay/return.py
+++ b/artiq/test/lit/iodelay/return.py
@@ -1,13 +1,13 @@
 # RUN: %python -m artiq.compiler.testbench.signature %s >%t
 # RUN: OutputCheck %s --file-to-check=%t
 
-# CHECK-L: f: ()->int(width=32) delay(30 mu)
+# CHECK-L: f: ()->numpy.int32 delay(30 mu)
 def f():
     for _ in range(10):
         delay_mu(3)
     return 10
 
-# CHECK-L: g: (x:float)->int(width=32)
+# CHECK-L: g: (x:float)->numpy.int32
 # CHECK-NOT-L: delay
 def g(x):
     if x > 1.0:
diff --git a/artiq/test/lit/iodelay/sequential.py b/artiq/test/lit/iodelay/sequential.py
index 54a776b68..5be751126 100644
--- a/artiq/test/lit/iodelay/sequential.py
+++ b/artiq/test/lit/iodelay/sequential.py
@@ -1,7 +1,7 @@
 # RUN: %python -m artiq.compiler.testbench.signature %s >%t
 # RUN: OutputCheck %s --file-to-check=%t
 
-# CHECK-L: f: (a:int(width=64), b:int(width=64))->NoneType delay(a + b mu)
+# CHECK-L: f: (a:numpy.int64, b:numpy.int64)->NoneType delay(a + b mu)
 def f(a, b):
     with sequential:
         delay_mu(a)
diff --git a/artiq/test/lit/monomorphism/integers.py b/artiq/test/lit/monomorphism/integers.py
index bc66bcc5a..5c0e8be7f 100644
--- a/artiq/test/lit/monomorphism/integers.py
+++ b/artiq/test/lit/monomorphism/integers.py
@@ -2,10 +2,10 @@
 # RUN: OutputCheck %s --file-to-check=%t
 
 x = 1
-# CHECK-L: x: int(width=32)
+# CHECK-L: x: numpy.int32
 
 y = int(1)
-# CHECK-L: y: int(width=32)
+# CHECK-L: y: numpy.int32
 
 z = round(1.0)
-# CHECK-L: z: int(width=32)
+# CHECK-L: z: numpy.int32