diff --git a/scripts/config/expr.c b/scripts/config/expr.c
index cbf4996dd9..8cee597d33 100644
--- a/scripts/config/expr.c
+++ b/scripts/config/expr.c
@@ -893,7 +893,10 @@ static enum string_value_kind expr_parse_string(const char *str,
 	switch (type) {
 	case S_BOOLEAN:
 	case S_TRISTATE:
-		return k_string;
+		val->s = !strcmp(str, "n") ? 0 :
+			 !strcmp(str, "m") ? 1 :
+			 !strcmp(str, "y") ? 2 : -1;
+		return k_signed;
 	case S_INT:
 		val->s = strtoll(str, &tail, 10);
 		kind = k_signed;