diff --git a/Objects/longobject.c b/Objects/longobject.c
index 9ca7b65..e2a4ef9 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -1887,7 +1887,7 @@
                         "int() arg 2 must be >= 2 and <= 36");
         return NULL;
     }
-    while (*str != '\0' && isspace(Py_CHARMASK(*str)))
+    while (*str != '\0' && Py_ISSPACE(Py_CHARMASK(*str)))
         str++;
     if (*str == '+')
         ++str;
@@ -2131,7 +2131,7 @@
         goto onError;
     if (sign < 0)
         Py_SIZE(z) = -(Py_SIZE(z));
-    while (*str && isspace(Py_CHARMASK(*str)))
+    while (*str && Py_ISSPACE(Py_CHARMASK(*str)))
         str++;
     if (*str != '\0')
         goto onError;
diff --git a/Objects/stringlib/formatter.h b/Objects/stringlib/formatter.h
index 139b56c..be0d897 100644
--- a/Objects/stringlib/formatter.h
+++ b/Objects/stringlib/formatter.h
@@ -414,7 +414,7 @@
     STRINGLIB_CHAR *end = ptr + len;
     STRINGLIB_CHAR *remainder;
 
-    while (ptr<end && isdigit(*ptr))
+    while (ptr<end && Py_ISDIGIT(*ptr))
         ++ptr;
     remainder = ptr;