diff --git a/include/cyclone/runtime.h b/include/cyclone/runtime.h
index 23c0c170..c74c82d0 100644
--- a/include/cyclone/runtime.h
+++ b/include/cyclone/runtime.h
@@ -440,12 +440,13 @@ object Cyc_is_list(object lst);
 #define Cyc_is_null(o) (make_boolean(o == NULL))
 //TODO: convert all of these to macros (if it makes sense, most should), and remove them from runtime.c:
 object Cyc_is_number(object o);
-object Cyc_is_complex(object o);
 object Cyc_is_real(object o);
 object Cyc_is_integer(object o);
 #define Cyc_is_fixnum(o) (make_boolean(obj_is_int(o)))
 //object Cyc_is_fixnum(object o);
 #define Cyc_is_bignum(o)     (make_boolean(is_object_type(o) && ((list) o)->tag == bignum_tag))
+//object Cyc_is_complex(object o);
+#define Cyc_is_complex(o)     (make_boolean(is_object_type(o) && ((list) o)->tag == complex_num_tag))
 //object Cyc_is_bignum(object o);
 //object Cyc_is_vector(object o);
 //object Cyc_is_bytevector(object o);
diff --git a/runtime.c b/runtime.c
index 249319e0..886e4b4d 100644
--- a/runtime.c
+++ b/runtime.c
@@ -1745,12 +1745,12 @@ object Cyc_is_real(object o)
   return boolean_f;
 }
 
-object Cyc_is_complex(object o)
-{
-  if ((o != NULL) && !is_value_type(o) && ((list) o)->tag == complex_num_tag)
-    return boolean_t;
-  return boolean_f;
-}
+//object Cyc_is_complex(object o)
+//{
+//  if ((o != NULL) && !is_value_type(o) && ((list) o)->tag == complex_num_tag)
+//    return boolean_t;
+//  return boolean_f;
+//}
 
 //object Cyc_is_fixnum(object o)
 //{