diff --git a/src/buffer/unicode.zig b/src/buffer/unicode.zig
index 8be7026..2da6d18 100644
--- a/src/buffer/unicode.zig
+++ b/src/buffer/unicode.zig
@@ -135,7 +135,7 @@ fn utf8_transform(comptime field: uucode.FieldEnum, allocator: std.mem.Allocator
     return result.toOwnedSlice();
 }
 
-fn utf8_predicate(comptime field: uucode.FieldEnum, text: []const u8) TransformError!bool {
+fn utf8_predicate(comptime field: uucode.FieldEnum, text: []const u8) error{InvalidUtf8}!bool {
     const view: std.unicode.Utf8View = try .init(text);
     var it = view.iterator();
     while (it.nextCodepoint()) |cp| {
@@ -177,5 +177,9 @@ pub fn switch_case(allocator: std.mem.Allocator, text: []const u8) TransformErro
         to_lower(allocator, text);
 }
 
+pub fn is_lowercase(text: []const u8) error{InvalidUtf8}!bool {
+    return try utf8_predicate(.is_lowercase, text);
+}
+
 const std = @import("std");
 const uucode = @import("vaxis").uucode;