diff --git a/build.zig b/build.zig
index 9ab5f74..39a5184 100644
--- a/build.zig
+++ b/build.zig
@@ -4,7 +4,7 @@ pub fn build(b: *std.Build) void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
 
-    _ = b.addModule("io", .{ .source_file = .{ .path = "src/io.zig" } });
+    _ = b.addModule("io", .{ .root_source_file = .{ .path = "src/io.zig" } });
 
     const main_tests = b.addTest(.{
         .root_source_file = .{ .path = "src/test.zig" },
diff --git a/src/io/linux.zig b/src/io/linux.zig
index eefb08c..dd6d838 100644
--- a/src/io/linux.zig
+++ b/src/io/linux.zig
@@ -957,7 +957,7 @@ pub const IO = struct {
         if (@hasDecl(os.O, "LARGEFILE")) flags |= os.O.LARGEFILE;
 
         var direct_io_supported = false;
-        var dir_on_tmpfs = try fs_is_tmpfs(dir_fd);
+        const dir_on_tmpfs = try fs_is_tmpfs(dir_fd);
 
         if (dir_on_tmpfs) {
             log.warn("tmpfs is not durable, and your data will be lost on reboot", .{});
diff --git a/src/io/windows.zig b/src/io/windows.zig
index 206b380..f7f3bc7 100644
--- a/src/io/windows.zig
+++ b/src/io/windows.zig
@@ -974,7 +974,7 @@ pub const IO = struct {
         }
 
         // O_EXCL
-        var shared_mode: os.windows.DWORD = 0;
+        const shared_mode: os.windows.DWORD = 0;
 
         // O_RDWR
         var access_mask: os.windows.DWORD = 0;