diff --git a/src/term.c b/src/term.c
index 0fdb33e..dd59fdf 100644
--- a/src/term.c
+++ b/src/term.c
@@ -3434,7 +3434,7 @@
 #endif
     {
 	env_colors = mch_getenv((char_u *)"COLORS");
-	if (env_colors != NULL && isdigit(*env_colors))
+	if (env_colors != NULL && SAFE_isdigit(*env_colors))
 	{
 	    int colors = atoi((char *)env_colors);
 
@@ -5849,7 +5849,7 @@
 	// characters.
 	for (i = j + 3; i < len; ++i)
 	{
-	    if (i - j == 3 && !isdigit(tp[i]))
+	    if (i - j == 3 && !SAFE_isdigit(tp[i]))
 		break;
 	    if (i - j == 4 && tp[i] != ' ')
 		break;
@@ -6083,7 +6083,7 @@
 			// The mouse termcode "ESC [" is also the prefix of
 			// "ESC [ I" (focus gained) and other keys.  Check some
 			// more bytes to find out.
-			if (!isdigit(tp[2]))
+			if (!SAFE_isdigit(tp[2]))
 			{
 			    // ESC [ without number following: Only use it when
 			    // there is no other match.
@@ -6166,7 +6166,7 @@
 			    // Skip over the digits, the final char must
 			    // follow. URXVT can use a negative value, thus
 			    // also accept '-'.
-			    for (j = slen - 2; j < len && (isdigit(tp[j])
+			    for (j = slen - 2; j < len && (SAFE_isdigit(tp[j])
 				       || tp[j] == '-' || tp[j] == ';'); ++j)
 				;
 			    ++j;