diff --git a/src/misc1.c b/src/misc1.c
index 5f9828e..dc0deae 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -975,9 +975,8 @@
 	c = safe_vgetc();
 	if (VIM_ISDIGIT(c))
 	{
-	    if (n > INT_MAX / 10)
+	    if (vim_append_digit_int(&n, c - '0') == FAIL)
 		return 0;
-	    n = n * 10 + c - '0';
 	    msg_putchar(c);
 	    ++typed;
 	}
@@ -2817,3 +2816,25 @@
     restore_v_event(v_event, &save_v_event);
 #endif
 }
+
+// For overflow detection, add a digit safely to an int value.
+    int
+vim_append_digit_int(int *value, int digit)
+{
+    int x = *value;
+    if (x > ((INT_MAX - digit) / 10))
+	return FAIL;
+    *value = x * 10 + digit;
+    return OK;
+}
+
+// For overflow detection, add a digit safely to a long value.
+    int
+vim_append_digit_long(long *value, int digit)
+{
+    long x = *value;
+    if (x > ((LONG_MAX - (long)digit) / 10))
+	return FAIL;
+    *value = x * 10 + (long)digit;
+    return OK;
+}