diff --git a/libavformat/swfdec.c b/libavformat/swfdec.c
index b2c652eb9c..db683ac59b 100644
--- a/libavformat/swfdec.c
+++ b/libavformat/swfdec.c
@@ -90,10 +90,10 @@ retry:
     z->avail_out = buf_size;
 
     ret = inflate(z, Z_NO_FLUSH);
-    if (ret < 0)
-        return AVERROR(EINVAL);
     if (ret == Z_STREAM_END)
         return AVERROR_EOF;
+    if (ret != Z_OK)
+        return AVERROR(EINVAL);
 
     if (buf_size - z->avail_out == 0)
         goto retry;