diff --git a/crates/mempool_node/build.rs b/crates/mempool_node/build.rs
new file mode 100644
index 0000000000..2c3d009e87
--- /dev/null
+++ b/crates/mempool_node/build.rs
@@ -0,0 +1,3 @@
+// Sets up the environment variable OUT_DIR, which holds the cairo compiler binary.
+// The binary is dowloaded to OUT_DIR by the starknet_sierra_compile crate.
+fn main() {}