diff --git a/include/cyclone/types.h b/include/cyclone/types.h
index ed33c9a5..85477af9 100644
--- a/include/cyclone/types.h
+++ b/include/cyclone/types.h
@@ -90,6 +90,9 @@ enum object_tag {
       , vector_tag              // 19
 };
 
+#define type_is_pair_prim(clo) \
+  (type_of(clo) >= pair_tag)
+
 // Define the size of object tags
 typedef unsigned char tag_type;
 
diff --git a/runtime.c b/runtime.c
index 75ccca58..7dc02591 100644
--- a/runtime.c
+++ b/runtime.c
@@ -79,7 +79,7 @@ void Cyc_check_bounds(void *data, const char *label, int len, int index)
 
 /* These macros are hardcoded here to support functions in this module. */
 #define closcall1(td, clo, a1) \
-if (type_of(clo) == pair_tag || prim(clo)) { \
+if (type_is_pair_prim(clo)) { \
    Cyc_apply(td, 0, (closure)(a1), clo); \
 } else { \
    ((clo)->fn)(td, 1, clo, a1);\
@@ -96,7 +96,7 @@ if (type_of(clo) == pair_tag || prim(clo)) { \
  } \
 }
 #define closcall2(td, clo, a1, a2) \
-if (type_of(clo) == pair_tag || prim(clo)) { \
+if (type_is_pair_prim(clo)) { \
    Cyc_apply(td, 1, (closure)(a1), clo,a2); \
 } else { \
   ((clo)->fn)(td, 2, clo, a1, a2);\
diff --git a/scheme/cyclone/cgen.sld b/scheme/cyclone/cgen.sld
index de825f8c..af9cfb1a 100644
--- a/scheme/cyclone/cgen.sld
+++ b/scheme/cyclone/cgen.sld
@@ -160,7 +160,7 @@
         (wrap (lambda (s) (if (> num-args 0) s ""))))
     (string-append
       "#define closcall" n "(td, clo" args ") \\\n"
-        (wrap (string-append "if (type_of(clo) == pair_tag || prim(clo)) { \\\n"
+        (wrap (string-append "if (type_is_pair_prim(clo)) { \\\n"
                              "   Cyc_apply(td, " n-1 ", (closure)(a1), clo" (if (> num-args 1) (substring args 3 (string-length args)) "") "); \\\n"
                              "}"))
         (wrap " else { \\\n")