diff --git a/src/Compilation.zig b/src/Compilation.zig
index 711b434c57d85cd9f6ae6df784f4b73a529b4b1e..610640d18e212787f9d43c95b63571d33b1f108d 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -6300,8 +6300,6 @@ fn addCommonCCArgs(
                 // LLVM doesn't distinguish between Solaris and illumos, but the illumos GCC fork
                 // defines this macro.
                 .illumos => try argv.append("__illumos__"),
-                // This macro has not yet been upstreamed by SerenityOS to Clang.
-                .serenity => try argv.append("__serenity__"),
                 // Homebrew targets without LLVM support; use communities's preferred macros.
                 .@"3ds" => try argv.append("-D__3DS__"),
                 .wiiu => try argv.append("-D__WIIU__"),