diff --git a/artiq/compiler/embedding.py b/artiq/compiler/embedding.py
index 2a6ce62c5..359584d6d 100644
--- a/artiq/compiler/embedding.py
+++ b/artiq/compiler/embedding.py
@@ -50,9 +50,22 @@ class EmbeddingMap:
         self.str_forward_map = {}
         self.str_reverse_map = {}
 
+        self.preallocate_runtime_exception_names(["RuntimeError",
+                                                  "RTIOUnderflow",
+                                                  "RTIOOverflow",
+                                                  "RTIODestinationUnreachable",
+                                                  "DMAError",
+                                                  "I2CError",
+                                                  "CacheError",
+                                                  "SPIError",
+                                                  "0:ZeroDivisionError",
+                                                  "0:IndexError"])
+
     def preallocate_runtime_exception_names(self, names):
         for i, name in enumerate(names):
-            exn_id = self.store_str("0:artiq.coredevice.exceptions." + name)
+            if ":" not in name:
+                name = "0:artiq.coredevice.exceptions." + name
+            exn_id = self.store_str(name)
             assert exn_id == i
 
     def store_str(self, s):
@@ -754,12 +767,6 @@ class Stitcher:
         self.functions = {}
 
         self.embedding_map = EmbeddingMap()
-        self.embedding_map.preallocate_runtime_exception_names(["runtimeerror",
-                                                                "RTIOUnderflow",
-                                                                "RTIOOverflow",
-                                                                "RTIODestinationUnreachable",
-                                                                "DMAError",
-                                                                "I2CError"])
         self.value_map = defaultdict(lambda: [])
         self.definitely_changed = False
 
diff --git a/artiq/compiler/module.py b/artiq/compiler/module.py
index 7f027ba2f..f3bc35cde 100644
--- a/artiq/compiler/module.py
+++ b/artiq/compiler/module.py
@@ -10,7 +10,7 @@ string and infers types for it using a trivial :module:`prelude`.
 
 import os
 from pythonparser import source, diagnostic, parse_buffer
-from . import prelude, types, transforms, analyses, validators
+from . import prelude, types, transforms, analyses, validators, embedding
 
 class Source:
     def __init__(self, source_buffer, engine=None):
@@ -18,7 +18,7 @@ class Source:
             self.engine = diagnostic.Engine(all_errors_are_fatal=True)
         else:
             self.engine = engine
-        self.embedding_map = None
+        self.embedding_map = embedding.EmbeddingMap()
         self.name, _ = os.path.splitext(os.path.basename(source_buffer.name))
 
         asttyped_rewriter = transforms.ASTTypedRewriter(engine=engine,
diff --git a/artiq/compiler/transforms/artiq_ir_generator.py b/artiq/compiler/transforms/artiq_ir_generator.py
index bd69ca79c..40f50718a 100644
--- a/artiq/compiler/transforms/artiq_ir_generator.py
+++ b/artiq/compiler/transforms/artiq_ir_generator.py
@@ -2814,14 +2814,15 @@ class ARTIQIRGenerator(algorithm.Visitor):
 
                 format_string += ")"
             elif builtins.is_exception(value.type):
+                # message may not be an actual string...
+                # so we cannot really print it
                 name    = self.append(ir.GetAttr(value, "#__name__"))
-                message = self.append(ir.GetAttr(value, "#__message__"))
                 param1  = self.append(ir.GetAttr(value, "#__param0__"))
                 param2  = self.append(ir.GetAttr(value, "#__param1__"))
                 param3  = self.append(ir.GetAttr(value, "#__param2__"))
 
-                format_string += "%.*s(%.*s, %lld, %lld, %lld)"
-                args += [name, message, param1, param2, param3]
+                format_string += "%ld(%lld, %lld, %lld)"
+                args += [name, param1, param2, param3]
             else:
                 assert False
 
diff --git a/artiq/test/lit/exceptions/catch_all.py b/artiq/test/lit/exceptions/catch_all.py
index 1417f5f31..1b4c38b8e 100644
--- a/artiq/test/lit/exceptions/catch_all.py
+++ b/artiq/test/lit/exceptions/catch_all.py
@@ -8,7 +8,7 @@ def catch(f):
     except Exception as e:
         print(e)
 
-# CHECK-L: ZeroDivisionError
+# CHECK-L: 8(0, 0, 0)
 catch(lambda: 1/0)
-# CHECK-L: IndexError
+# CHECK-L: 9(10, 1, 0)
 catch(lambda: [1.0][10])
diff --git a/artiq/test/lit/exceptions/catch_multi.py b/artiq/test/lit/exceptions/catch_multi.py
index 472086660..dbd8bcdec 100644
--- a/artiq/test/lit/exceptions/catch_multi.py
+++ b/artiq/test/lit/exceptions/catch_multi.py
@@ -10,7 +10,7 @@ def catch(f):
     except IndexError as ie:
         print(ie)
 
-# CHECK-L: ZeroDivisionError
+# CHECK-L: 8(0, 0, 0)
 catch(lambda: 1/0)
-# CHECK-L: IndexError
+# CHECK-L: 9(10, 1, 0)
 catch(lambda: [1.0][10])
diff --git a/artiq/test/lit/exceptions/reraise.py b/artiq/test/lit/exceptions/reraise.py
index 911b22322..fd5eabd4a 100644
--- a/artiq/test/lit/exceptions/reraise.py
+++ b/artiq/test/lit/exceptions/reraise.py
@@ -3,7 +3,7 @@
 # REQUIRES: exceptions
 
 def f():
-    # CHECK-L: Uncaught 0:ZeroDivisionError
+    # CHECK-L: Uncaught 8
     # CHECK-L: at input.py:${LINE:+1}:
     1/0
 
diff --git a/artiq/test/lit/exceptions/reraise_update.py b/artiq/test/lit/exceptions/reraise_update.py
index 11bd30639..aac8cdae1 100644
--- a/artiq/test/lit/exceptions/reraise_update.py
+++ b/artiq/test/lit/exceptions/reraise_update.py
@@ -9,7 +9,7 @@ def g():
     try:
         f()
     except Exception as e:
-        # CHECK-L: Uncaught 0:ZeroDivisionError
+        # CHECK-L: Uncaught 8
         # CHECK-L: at input.py:${LINE:+1}:
         raise e
 
diff --git a/artiq/test/lit/exceptions/uncaught.py b/artiq/test/lit/exceptions/uncaught.py
index 13b83ec22..1d44d4b2a 100644
--- a/artiq/test/lit/exceptions/uncaught.py
+++ b/artiq/test/lit/exceptions/uncaught.py
@@ -2,6 +2,6 @@
 # RUN: OutputCheck %s --file-to-check=%t
 # REQUIRES: exceptions
 
-# CHECK-L: Uncaught 0:ZeroDivisionError: cannot divide by zero (0, 0, 0)
+# CHECK-L: Uncaught 8: cannot divide by zero (0, 0, 0)
 # CHECK-L: at input.py:${LINE:+1}:
 1/0