diff --git a/lib/curl_ctype.h b/lib/curl_ctype.h
index 8eb41727b4..48c3c37c35 100644
--- a/lib/curl_ctype.h
+++ b/lib/curl_ctype.h
@@ -43,7 +43,7 @@
 #define ISLOWER(x)  (((x) >= 'a') && ((x) <= 'z'))
 #define ISDIGIT(x)  (((x) >= '0') && ((x) <= '9'))
 #define ISBLANK(x)  (((x) == ' ') || ((x) == '\t'))
-#define ISSPACE(x)  ISBLANK(x)
+#define ISSPACE(x)  (ISBLANK(x) || (((x) >= 0xa) && ((x) <= 0x0d)))
 #define ISURLPUNTCS(x) (((x) == '-') || ((x) == '.') || ((x) == '_') || \
                         ((x) == '~'))
 #define ISUNRESERVED(x) (ISALNUM(x) || ISURLPUNTCS(x))