diff --git a/src/lib.zig b/src/lib.zig
index e9b876240919d39b0ce5dd3ae5a2e7853d8161a4..4b26058d61f7a3603440aec29b89e48defea2ed1 100644
--- a/src/lib.zig
+++ b/src/lib.zig
@@ -34,7 +34,7 @@ pub fn addSentinel(alloc: *std.mem.Allocator, comptime T: type, input: []const T
 
 const alphabet = "0123456789abcdefghijklmnopqrstuvwxyz";
 
-pub fn randomSlice(alloc: *std.mem.Allocator, rand: *std.rand.Random, comptime T: type, len: usize) ![]const T {
+pub fn randomSlice(alloc: *std.mem.Allocator, rand: *std.rand.Random, comptime T: type, len: usize) ![]T {
     var buf = try alloc.alloc(T, len);
     var i: usize = 0;
     while (i < len) : (i += 1) {
@@ -56,7 +56,7 @@ pub fn base64EncodeAlloc(alloc: *std.mem.Allocator, input: string) !string {
     return base64.encode(buf, input);
 }
 
-pub fn asciiUpper(alloc: *std.mem.Allocator, input: string) !string {
+pub fn asciiUpper(alloc: *std.mem.Allocator, input: string) ![]u8 {
     var buf = try alloc.dupe(u8, input);
     for (range(buf.len)) |_, i| {
         buf[i] = std.ascii.toUpper(buf[i]);