diff --git a/src/audio/SDL_audiocvt.c b/src/audio/SDL_audiocvt.c
index dbae813ae..870d8cd28 100755
--- a/src/audio/SDL_audiocvt.c
+++ b/src/audio/SDL_audiocvt.c
@@ -295,8 +295,9 @@ SDL_ConvertStereo(SDL_AudioCVT * cvt, SDL_AudioFormat format)
     { \
         const type *src = (const type *) (cvt->buf + cvt->len_cvt); \
         type *dst = (type *) (cvt->buf + cvt->len_cvt * 2); \
-        for (i = cvt->len_cvt / sizeof(type); i; --i, --src) { \
+        for (i = cvt->len_cvt / sizeof(type); i; --i) { \
             const type val = *src; \
+            src -= 1; \
             dst -= 2; \
             dst[0] = dst[1] = val; \
         } \