diff --git a/sdk/include/crt/math.h b/sdk/include/crt/math.h
index b6ab12c8313..f565491ad6a 100644
--- a/sdk/include/crt/math.h
+++ b/sdk/include/crt/math.h
@@ -270,6 +270,7 @@ _Check_return_ __CRT_INLINE long lrintl(_In_ long double x) { return (long)((x <
 _Check_return_ __CRT_INLINE long long llrint(_In_ double x) { return (long long)((x < 0) ? (x - 0.5f) : (x + 0.5)); }
 _Check_return_ __CRT_INLINE long long llrintf(_In_ float x) { return (long long)((x < 0) ? (x - 0.5f) : (x + 0.5)); }
 _Check_return_ __CRT_INLINE long long llrintl(_In_ long double x) { return (long long)((x < 0) ? (x - 0.5f) : (x + 0.5)); }
+_Check_return_ __CRT_INLINE double log2(_In_ double x) { return log(x) / log(2); }
 
 #ifndef NO_OLDNAMES /* !__STDC__ */