diff --git a/libavcodec/hdrdec.c b/libavcodec/hdrdec.c
index cffa7570db..1a6935ff75 100644
--- a/libavcodec/hdrdec.c
+++ b/libavcodec/hdrdec.c
@@ -72,7 +72,7 @@ static int decompress(uint8_t *scanline, int w, GetByteContext *gb, const uint8_
             for (int i = run << rshift; i > 0 && w > 0 && scanline >= start + 4; i--) {
                 memcpy(scanline, scanline - 4, 4);
                 scanline += 4;
-                w -= 4;
+                w--;
             }
             rshift += 8;
             if (rshift > 16)