diff --git a/.gitignore b/.gitignore
index 7399b15..0f6dd42 100644
--- a/.gitignore
+++ b/.gitignore
@@ -42,6 +42,7 @@ Temporary Items
 # Zig programming language
 
 zig-cache/
+.zig-cache/
 zig-out/
 build/
 build-*/
diff --git a/build.zig b/build.zig
index 8181ae5..6fd870c 100644
--- a/build.zig
+++ b/build.zig
@@ -25,16 +25,14 @@ pub fn build(b: *std.Build) void {
     _ = b.addModule(
         "jstring",
         .{
-            .root_source_file = .{ .path = "src/jstring.zig" },
+            .root_source_file = b.path("src/jstring.zig"),
         },
     );
 
     _ = b.addModule(
         "pcre_binding.c",
         .{
-            .root_source_file = .{
-                .path = b.pathFromRoot("src/pcre/pcre_binding.c"),
-            },
+            .root_source_file = b.path("src/pcre/pcre_binding.c"),
         },
     );
 
@@ -47,7 +45,7 @@ pub fn build(b: *std.Build) void {
     obj_pcre_binding.linkLibC();
     obj_pcre_binding.addCSourceFile(
         .{
-            .file = .{ .path = "src/pcre/pcre_binding.c" },
+            .file = b.path("src/pcre/pcre_binding.c"),
             .flags = &.{"-std=c17"},
         },
     );
@@ -66,7 +64,7 @@ pub fn build(b: *std.Build) void {
 
     const jstring_lib = b.addStaticLibrary(.{
         .name = "jstring",
-        .root_source_file = .{ .path = "src/jstring.zig" },
+        .root_source_file = b.path("src/jstring.zig"),
         .target = target,
         .optimize = optimize,
     });
diff --git a/src/jstring.zig b/src/jstring.zig
index 147422d..f4e32c3 100644
--- a/src/jstring.zig
+++ b/src/jstring.zig
@@ -180,7 +180,7 @@ pub const JString = struct {
 
     // ** at
 
-    pub inline fn at(this: *JString, index: isize) !u21 {
+    pub inline fn at(this: *const JString, index: isize) !u21 {
         return this.unmanaged.at(index);
     }
 
@@ -948,7 +948,7 @@ pub const JStringUnmanaged = struct {
     /// different to Javascript's string.at, return unicode char(u21) of index, as prefer utf-8 string. Same to
     /// Javascript, accept index as `i32`: when postive is from beginning; when negative is from ending; when
     /// `index == 0`, return the the first char if not empty.
-    pub fn at(this: *JStringUnmanaged, index: isize) Error!u21 {
+    pub fn at(this: *const JStringUnmanaged, index: isize) Error!u21 {
         const utf8_len = try this.utf8Len();
         if (index >= utf8_len) {
             return error.IndexOutOfBounds;