diff --git a/artiq/protocols/pyon.py b/artiq/protocols/pyon.py
index 8577896ed..922b94a1b 100644
--- a/artiq/protocols/pyon.py
+++ b/artiq/protocols/pyon.py
@@ -49,8 +49,8 @@ _encode_map = {
 _numpy_scalar = {
     "int8", "int16", "int32", "int64",
     "uint8", "uint16", "uint32", "uint64",
-    "float16", "float32", "float64", "float128",
-    "complex64", "complex128", "complex256",
+    "float16", "float32", "float64",
+    "complex64", "complex128",
 }