diff --git a/artiq/__init__.py b/artiq/__init__.py
index 7e6404c1e..ae6a8f96b 100644
--- a/artiq/__init__.py
+++ b/artiq/__init__.py
@@ -1,2 +1,5 @@
 from artiq import language
 from artiq.language import *
+
+__all__ = []
+__all__.extend(language.__all__)
diff --git a/artiq/language/__init__.py b/artiq/language/__init__.py
index ebdb62601..ad51894b5 100644
--- a/artiq/language/__init__.py
+++ b/artiq/language/__init__.py
@@ -1,4 +1,11 @@
+from artiq.language import core, experiment, db, units
 from artiq.language.core import *
-from artiq.language.experiment import Experiment
+from artiq.language.experiment import *
 from artiq.language.db import *
 from artiq.language.units import *
+
+__all__ = []
+__all__.extend(core.__all__)
+__all__.extend(experiment.__all__)
+__all__.extend(db.__all__)
+__all__.extend(units.__all__)
diff --git a/artiq/language/core.py b/artiq/language/core.py
index 340ea2374..051ef64c1 100644
--- a/artiq/language/core.py
+++ b/artiq/language/core.py
@@ -2,8 +2,20 @@
 Core ARTIQ extensions to the Python language.
 """
 
-from collections import namedtuple as _namedtuple
-from functools import wraps as _wraps
+from collections import namedtuple
+from functools import wraps
+
+
+__all__ = ["int64", "round64", "kernel", "portable",
+           "set_time_manager", "set_syscall_manager", "set_watchdog_factory",
+           "RuntimeException"]
+
+# global namespace for kernels
+kernel_globals = ("sequential", "parallel",
+    "delay_mu", "now_mu", "at_mu", "delay",
+    "seconds_to_mu", "mu_to_seconds",
+    "syscall", "watchdog")
+__all__.extend(kernel_globals)
 
 
 class int64(int):
@@ -65,7 +77,7 @@ def round64(x):
     return int64(round(x))
 
 
-_KernelFunctionInfo = _namedtuple("_KernelFunctionInfo", "core_name k_function")
+_KernelFunctionInfo = namedtuple("_KernelFunctionInfo", "core_name k_function")
 
 
 def kernel(arg):
@@ -89,16 +101,16 @@ def kernel(arg):
     """
     if isinstance(arg, str):
         def real_decorator(k_function):
-            @_wraps(k_function)
+            @wraps(k_function)
             def run_on_core(exp, *k_args, **k_kwargs):
-                return getattr(exp, arg).run(k_function, 
+                return getattr(exp, arg).run(k_function,
                                              ((exp,) + k_args), k_kwargs)
             run_on_core.k_function_info = _KernelFunctionInfo(
                 core_name=arg, k_function=k_function)
             return run_on_core
         return real_decorator
     else:
-        @_wraps(arg)
+        @wraps(arg)
         def run_on_core(exp, *k_args, **k_kwargs):
             return exp.core.run(arg, ((exp,) + k_args), k_kwargs)
         run_on_core.k_function_info = _KernelFunctionInfo(
@@ -160,13 +172,6 @@ def set_syscall_manager(syscall_manager):
     global _syscall_manager
     _syscall_manager = syscall_manager
 
-# global namespace for kernels
-
-kernel_globals = ("sequential", "parallel",
-    "delay_mu", "now_mu", "at_mu", "delay",
-    "seconds_to_mu", "mu_to_seconds",
-    "syscall", "watchdog")
-
 
 class _Sequential:
     """In a sequential block, statements are executed one after another, with
diff --git a/artiq/language/db.py b/artiq/language/db.py
index 025dc22d2..d5f055603 100644
--- a/artiq/language/db.py
+++ b/artiq/language/db.py
@@ -2,6 +2,9 @@
 Connection to device, parameter and result database.
 """
 
+__all__ = ["Device", "NoDefault", "Parameter", "Argument", "Result", "AutoDB"]
+
+
 class _AttributeKind:
     pass
 
diff --git a/artiq/language/experiment.py b/artiq/language/experiment.py
index 3473dcba3..c7fce7a55 100644
--- a/artiq/language/experiment.py
+++ b/artiq/language/experiment.py
@@ -1,5 +1,7 @@
 from inspect import isclass
 
+__all__ = ["Experiment", "has_analyze", "is_experiment"]
+
 
 class Experiment:
     """Base class for experiments.
diff --git a/artiq/language/units.py b/artiq/language/units.py
index b3af0ebc3..83f1133a8 100644
--- a/artiq/language/units.py
+++ b/artiq/language/units.py
@@ -1,3 +1,5 @@
+__all__ = []
+
 _prefixes_str = "pnum_kMG"
 _smallest_prefix_exp = -12
 
@@ -8,6 +10,7 @@ def _register_unit(unit, prefixes):
         if prefix in prefixes:
             full_name = prefix + unit if prefix != "_" else unit
             globals()[full_name] = 10.**exponent
+            __all__.append(full_name)
         exponent += 3