diff --git a/Parser/pgen.c b/Parser/pgen.c
index b2f8470..f3031ae 100644
--- a/Parser/pgen.c
+++ b/Parser/pgen.c
@@ -136,11 +136,12 @@
 
 static char REQNFMT[] = "metacompile: less than %d children\n";
 
-#define REQN(i, count) \
+#define REQN(i, count) do { \
     if (i < count) { \
         fprintf(stderr, REQNFMT, count); \
         Py_FatalError("REQN"); \
-    } else
+    } \
+} while (0)
 
 #else
 #define REQN(i, count)  /* empty */