diff --git a/chained/water_impl.go b/chained/water_impl.go
index bcd2951ca..98b45083a 100644
--- a/chained/water_impl.go
+++ b/chained/water_impl.go
@@ -35,7 +35,7 @@ var (
 	// foo.wasm file or read the foo.wasm file on disk.
 	//
 	// Invariant: entries to this map are never overwritten.
-	waterWASMLocks map[string]*sync.Mutex
+	waterWASMLocks = make(map[string]*sync.Mutex)
 	// wlLock protects access to the waterWASMLocks map.
 	wlLock = new(sync.Mutex)
 )