diff --git a/libavcodec/x86/cpuid.c b/libavcodec/x86/cpuid.c
index 1ed4d2e7e3..832b9909dc 100644
--- a/libavcodec/x86/cpuid.c
+++ b/libavcodec/x86/cpuid.c
@@ -98,7 +98,7 @@ int mm_support(void)
 
     if(max_ext_level >= 0x80000001){
         cpuid(0x80000001, eax, ebx, ecx, ext_caps);
-        if (ext_caps & (1<<31))
+        if (ext_caps & (1U<<31))
             rval |= FF_MM_3DNOW;
         if (ext_caps & (1<<30))
             rval |= FF_MM_3DNOWEXT;