diff --git a/flake.nix b/flake.nix
index 25ffc70205..b362df4d07 100644
--- a/flake.nix
+++ b/flake.nix
@@ -78,6 +78,8 @@
 
             # Ugly hack to make the Clang resources directory available.
             export GOFLAGS="\"-ldflags=-X github.com/tinygo-org/tinygo/goenv.clangResourceDir=${llvmPackages_18.clang.cc.lib}/lib/clang/18\" -tags=llvm18"
+
+            export CGO_CPPFLAGS="-I${llvmPackages_18.llvm.dev}/include/llvm-18 -I${llvmPackages_18.llvm.dev}/include/llvm-c-18"
           '';
         };
       }