diff --git a/.changeset/spicy-points-melt.md b/.changeset/spicy-points-melt.md
new file mode 100644
index 0000000..f7beb51
--- /dev/null
+++ b/.changeset/spicy-points-melt.md
@@ -0,0 +1,5 @@
+---
+"@copepod/kv": patch
+---
+
+Filenames were not interpolated correctly in **fs-composite**.
diff --git a/packages/kv/src/fs-composite.ts b/packages/kv/src/fs-composite.ts
index 45a150e..0f9f76a 100644
--- a/packages/kv/src/fs-composite.ts
+++ b/packages/kv/src/fs-composite.ts
@@ -122,7 +122,7 @@ export default class CompositeStore implements Store<object> {
 		for (const interpolator of this.interpolators) {
 			interpolated.push(interpolator === '__hash' ? await hash(key) : extract(key, interpolator) ?? '')
 		}
-		return paths.join(this.root, String.raw({ raw: this.raws }, interpolated))
+		return paths.join(this.root, String.raw({ raw: this.raws }, ...interpolated))
 	}
 
 	async get(key: object): Promise<Uint8Array | undefined> {