diff --git a/ext/standard/file.c b/ext/standard/file.c
index 65bd7b8e3d6..fa7649b45c6 100644
--- a/ext/standard/file.c
+++ b/ext/standard/file.c
@@ -2529,7 +2529,7 @@ PHP_FUNCTION(fgetcsv)
 	lineEnd = emalloc(len + 1);
 	bptr = buf;
 	tptr = buf + strlen(buf) -1;
-	while ( isspace((int) *tptr) && (*tptr!=delimiter) && (tptr > bptr) ) tptr--;
+	while ( isspace((int)*(unsigned char *)tptr) && (*tptr!=delimiter) && (tptr > bptr) ) tptr--;
 	tptr++;
 	strcpy(lineEnd, tptr);
 
@@ -2551,7 +2551,7 @@ PHP_FUNCTION(fgetcsv)
 
 	do {
 		/* 1. Strip any leading space */
-		while(isspace((int) *bptr) && (*bptr!=delimiter)) bptr++;
+		while(isspace((int)*(unsigned char *)bptr) && (*bptr!=delimiter)) bptr++;
 		/* 2. Read field, leaving bptr pointing at start of next field */
 		if (enclosure && *bptr == enclosure) {
 			bptr++;	/* move on to first character in field */
@@ -2600,7 +2600,7 @@ PHP_FUNCTION(fgetcsv)
 						temp = erealloc(temp, temp_len+1);
 						bptr = buf;
 						tptr = buf + strlen(buf) -1;
-						while (isspace((int) *tptr) && (*tptr!=delimiter) && (tptr > bptr)) 
+						while (isspace((int)*(unsigned char *)tptr) && (*tptr!=delimiter) && (tptr > bptr)) 
 							tptr--;
 						tptr++; 
 						strcpy(lineEnd, tptr);
@@ -2621,7 +2621,7 @@ PHP_FUNCTION(fgetcsv)
 
 			if (strlen(temp)) {
 				tptr--;
-				while (isspace((int)*tptr) && (*tptr!=delimiter)) 
+				while (isspace((int)*(unsigned char *)tptr) && (*tptr!=delimiter)) 
 					*tptr-- = 0;	/* strip any trailing spaces */
 			}