diff --git a/src/charset.c b/src/charset.c
index 826a768..6b2790f 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -2138,7 +2138,8 @@
     varnumber_T		*nptr,	    // return: signed result
     uvarnumber_T	*unptr,	    // return: unsigned result
     int			maxlen,     // max length of string to check
-    int			strict)     // check strictly
+    int			strict,     // check strictly
+    int			*overflow)  // when not NULL set to TRUE for overflow
 {
     char_u	    *ptr = start;
     int		    pre = 0;		// default is decimal
@@ -2209,7 +2210,11 @@
 	    if (un <= UVARNUM_MAX / 2)
 		un = 2 * un + (uvarnumber_T)(*ptr - '0');
 	    else
+	    {
 		un = UVARNUM_MAX;
+		if (overflow != NULL)
+		    *overflow = TRUE;
+	    }
 	    ++ptr;
 	    if (n++ == maxlen)
 		break;
@@ -2234,7 +2239,11 @@
 	    if (un <= UVARNUM_MAX / 8)
 		un = 8 * un + (uvarnumber_T)(*ptr - '0');
 	    else
+	    {
 		un = UVARNUM_MAX;
+		if (overflow != NULL)
+		    *overflow = TRUE;
+	    }
 	    ++ptr;
 	    if (n++ == maxlen)
 		break;
@@ -2258,7 +2267,11 @@
 	    if (un <= UVARNUM_MAX / 16)
 		un = 16 * un + (uvarnumber_T)hex2nr(*ptr);
 	    else
+	    {
 		un = UVARNUM_MAX;
+		if (overflow != NULL)
+		    *overflow = TRUE;
+	    }
 	    ++ptr;
 	    if (n++ == maxlen)
 		break;
@@ -2282,7 +2295,11 @@
 		    || (un == UVARNUM_MAX / 10 && digit <= UVARNUM_MAX % 10))
 		un = 10 * un + digit;
 	    else
+	    {
 		un = UVARNUM_MAX;
+		if (overflow != NULL)
+		    *overflow = TRUE;
+	    }
 	    ++ptr;
 	    if (n++ == maxlen)
 		break;
@@ -2310,7 +2327,11 @@
 	{
 	    // avoid ubsan error for overflow
 	    if (un > VARNUM_MAX)
+	    {
 		*nptr = VARNUM_MIN;
+		if (overflow != NULL)
+		    *overflow = TRUE;
+	    }
 	    else
 		*nptr = -(varnumber_T)un;
 	}
@@ -2318,7 +2339,11 @@
 	{
 	    // prevent a large unsigned number to become negative
 	    if (un > VARNUM_MAX)
+	    {
 		un = VARNUM_MAX;
+		if (overflow != NULL)
+		    *overflow = TRUE;
+	    }
 	    *nptr = (varnumber_T)un;
 	}
     }