diff --git a/artiq/compiler/transforms/llvm_ir_generator.py b/artiq/compiler/transforms/llvm_ir_generator.py
index b2fea1852..25d7c6859 100644
--- a/artiq/compiler/transforms/llvm_ir_generator.py
+++ b/artiq/compiler/transforms/llvm_ir_generator.py
@@ -1546,8 +1546,8 @@ class LLVMIRGenerator:
             lleltsptr = llglobal.bitcast(lleltsary.type.element.as_pointer())
             llconst   = ll.Constant(llty, [lleltsptr, ll.Constant(lli32, len(llelts))])
             return llconst
-        elif types.is_rpc(typ) or types.is_c_function(typ):
-            # RPC and C functions have no runtime representation.
+        elif types.is_rpc(typ) or types.is_c_function(typ) or types.is_builtin_function(typ):
+            # RPC, C and builtin functions have no runtime representation.
             return ll.Constant(llty, ll.Undefined)
         elif types.is_function(typ):
             try:
diff --git a/artiq/compiler/types.py b/artiq/compiler/types.py
index be76adf5a..6e5015f48 100644
--- a/artiq/compiler/types.py
+++ b/artiq/compiler/types.py
@@ -605,6 +605,14 @@ def is_builtin(typ, name=None):
         return isinstance(typ, TBuiltin) and \
             typ.name == name
 
+def is_builtin_function(typ, name=None):
+    typ = typ.find()
+    if name is None:
+        return isinstance(typ, TBuiltinFunction)
+    else:
+        return isinstance(typ, TBuiltinFunction) and \
+            typ.name == name
+
 def is_constructor(typ, name=None):
     typ = typ.find()
     if name is not None:
diff --git a/artiq/test/coredevice/test_embedding.py b/artiq/test/coredevice/test_embedding.py
index 26277a7c9..b0bcbbed3 100644
--- a/artiq/test/coredevice/test_embedding.py
+++ b/artiq/test/coredevice/test_embedding.py
@@ -211,6 +211,10 @@ class _RPCCalls(EnvExperiment):
     def numpy_full(self):
         return numpy.full(10, 20)
 
+    @kernel
+    def numpy_nan(self):
+        return numpy.full(10, numpy.nan)
+
     @kernel
     def builtin(self):
         sleep(1.0)
@@ -229,6 +233,7 @@ class RPCCallsTest(ExperimentCase):
         self.assertEqual(exp.numpy_things(),
                          (numpy.int32(10), numpy.int64(20), numpy.array([42,])))
         self.assertTrue((exp.numpy_full() == numpy.full(10, 20)).all())
+        self.assertTrue(numpy.isnan(exp.numpy_nan()).all())
         exp.builtin()