diff --git a/libavcodec/internal.h b/libavcodec/internal.h
index b8ceb2e9f1..f4e12e8084 100644
--- a/libavcodec/internal.h
+++ b/libavcodec/internal.h
@@ -35,7 +35,7 @@
 
 #define FF_SANE_NB_CHANNELS 63U
 
-#define FF_SIGNBIT(x) (x >> CHAR_BIT * sizeof(x) - 1)
+#define FF_SIGNBIT(x) ((x) >> CHAR_BIT * sizeof(x) - 1)
 
 #if HAVE_AVX
 #   define STRIDE_ALIGN 32