diff --git a/compiler/sigmatch.nim b/compiler/sigmatch.nim
index 1bf4e13a305ba..a96a9abbc436a 100644
--- a/compiler/sigmatch.nim
+++ b/compiler/sigmatch.nim
@@ -239,7 +239,8 @@ proc sumGeneric(t: PType): int =
           result += sumGeneric(a)
       break
     of tyProc:
-      result += sumGeneric(t.returnType)
+      if t.returnType != nil:
+        result += sumGeneric(t.returnType)
       for _, a in t.paramTypes:
         result += sumGeneric(a)
       break