diff --git a/libavutil/qsort.h b/libavutil/qsort.h
index ca66c5fb62..0b352cf164 100644
--- a/libavutil/qsort.h
+++ b/libavutil/qsort.h
@@ -25,7 +25,7 @@
     void *stack[64][2];\
     int sp= 1;\
     stack[0][0] = p;\
-    stack[0][1] = p+num-1;\
+    stack[0][1] = (p)+(num)-1;\
     while(sp){\
         type *start= stack[--sp][0];\
         type *end  = stack[  sp][1];\