--- a/crates/bender-slang/build.rs
+++ b/crates/bender-slang/build.rs
@@ -55,6 +55,9 @@
         .define("CMAKE_DISABLE_FIND_PACKAGE_fmt", "ON")
         .define("CMAKE_DISABLE_FIND_PACKAGE_mimalloc", "ON")
         .define("CMAKE_DISABLE_FIND_PACKAGE_Boost", "ON")
+        .define("FETCHCONTENT_SOURCE_DIR_SLANG", "@slangSrc@")
+        .define("FETCHCONTENT_SOURCE_DIR_FMT", "@fmtSrc@")
+        .define("FETCHCONTENT_SOURCE_DIR_MIMALLOC", "@mimallocSrc@")
         .profile(cmake_profile);

     // Apply common defines and flags
@@ -71,9 +74,9 @@
     // With FetchContent, cmake builds slang in a _deps subdirectory rather than
     // installing it. Point directly at the FetchContent build/source directories.
     let slang_lib_dir = dst.join("build/_deps/slang-build/lib");
-    let slang_include_dir = dst.join("build/_deps/slang-src/include");
+    let slang_include_dir = std::path::PathBuf::from("@slangSrc@").join("include");
     let slang_generated_include_dir = dst.join("build/_deps/slang-build/source");
-    let fmt_include_dir = dst.join("build/_deps/fmt-src/include");
+    let fmt_include_dir = std::path::PathBuf::from("@fmtSrc@").join("include");

     // Generate cpp/compile_flags.txt for clangd IDE support
     if !in_publish {