diff --git a/common/base.c b/common/base.c
index 8e17e748bb364ed266a7d7f8439f9a5242c1878c..ce6614fbea4afac5c56ee74f2a187d97724799ad 100644
--- a/common/base.c
+++ b/common/base.c
@@ -35,6 +35,8 @@
 #include <sys/mman.h>
 #endif
 
+#define X264_ISDIGIT(x) isdigit((unsigned char)(x))
+
 /****************************************************************************
  * x264_reduce_fraction:
  ****************************************************************************/
@@ -922,7 +924,7 @@ REALIGN_STACK int x264_param_parse( x264_param_t *p, const char *name, const cha
     if( 0 );
     OPT("asm")
     {
-        p->cpu = isdigit(value[0]) ? (uint32_t)atoi(value) :
+        p->cpu = X264_ISDIGIT(value[0]) ? (uint32_t)atoi(value) :
                  !strcasecmp(value, "auto") || atobool(value) ? x264_cpu_detect() : 0;
         if( b_error )
         {
diff --git a/common/base.h b/common/base.h
index 40957ecdcec56288c65b4d2390bb40df829a7519..857c0fc47d74cd08a8129b847e1e985577ae2e86 100644
--- a/common/base.h
+++ b/common/base.h
@@ -82,7 +82,7 @@ typedef union { x264_uint128_t i; uint64_t q[2]; uint32_t d[4]; uint16_t w[8]; u
 #define MEM_DYN(x, t) (*(t (*)[])(x))
 #else
 //older versions of gcc prefer casting to structure instead of array
-#define MEM_FIX(x, t, s) (*(struct { t a[s]; } (*))(x))
+#define MEM_FIX(x, t, s) (*(struct { t a[s]; } MAY_ALIAS (*))(x))
 //let's set an arbitrary large constant size
 #define MEM_DYN(x, t) MEM_FIX(x, t, 4096)
 #endif
diff --git a/tools/checkasm.c b/tools/checkasm.c
index 9b59c1e18baa2a03e3ea7895a047cbc62a17f1d9..829f3e26128ce8c0e09b91c554a489cf646316e2 100644
--- a/tools/checkasm.c
+++ b/tools/checkasm.c
@@ -54,6 +54,8 @@ static pixel *pbuf3, *pbuf4;
 #define FMT_PIXEL "%02x"
 #endif
 
+#define X264_ISDIGIT(x) isdigit((unsigned char)(x))
+
 static int quiet = 0;
 
 #define report( name ) { \
@@ -148,8 +150,8 @@ static int cmp_bench( const void *a, const void *b )
     {
         if( !*sa && !*sb )
             return 0;
-        if( isdigit( *sa ) && isdigit( *sb ) && isdigit( sa[1] ) != isdigit( sb[1] ) )
-            return isdigit( sa[1] ) - isdigit( sb[1] );
+        if( X264_ISDIGIT( *sa ) && X264_ISDIGIT( *sb ) && X264_ISDIGIT( sa[1] ) != X264_ISDIGIT( sb[1] ) )
+            return X264_ISDIGIT( sa[1] ) - X264_ISDIGIT( sb[1] );
         if( *sa != *sb )
             return *sa - *sb;
     }