diff --git a/Parser/myreadline.c b/Parser/myreadline.c
index 29b254f771f..e8e57738f33 100644
--- a/Parser/myreadline.c
+++ b/Parser/myreadline.c
@@ -318,7 +318,7 @@ PyOS_StdioReadline(FILE *sys_stdin, FILE *sys_stdout, const char *prompt)
             return NULL;
         }
         p = pr;
-        int err = my_fgets(tstate, p + n, incr, sys_stdin);
+        int err = my_fgets(tstate, p + n, (int)incr, sys_stdin);
         if (err == 1) {
             // Interrupt
             PyMem_RawFree(p);