diff --git a/src/types/coinselect.d.ts b/src/types/coinselect.d.ts
new file mode 100644
index 0000000..bae9bbb
--- /dev/null
+++ b/src/types/coinselect.d.ts
@@ -0,0 +1,21 @@
+declare module "coinselect" {
+
+  interface Output {
+    address: string;
+    value: number;
+  }
+
+  interface CoinSelectResponse<T> {
+    inputs: T[];
+    outputs: Output[];
+    fee: number;
+  }
+
+  function coinselect<T>(
+    utxos: T[],
+    outputs: Output[],
+    feeRate: number
+  ): CoinSelectResponse<T>;
+
+  export default coinselect;
+}