diff --git a/src/Compilation.zig b/src/Compilation.zig
index 90df796fe59cb098350a203b1e4021e345d185e5..98de2b172c03bafc6181d2a9dd8e3e64c726b1b7 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -6358,8 +6358,6 @@ fn addCommonCCArgs(
                 // LLVM doesn't distinguish between Solaris and illumos, but the illumos GCC fork
                 // defines this macro.
                 .illumos => try argv.append("-D__illumos__"),
-                // This macro has not yet been upstreamed by SerenityOS to Clang.
-                .serenity => try argv.append("-D__serenity__"),
                 // Homebrew targets without LLVM support; use communities's preferred macros.
                 .@"3ds" => try argv.append("-D__3DS__"),
                 .wiiu => try argv.append("-D__WIIU__"),