diff --git a/contracts/Storage.sol b/contracts/Storage.sol
index 04ba9a6..9e692c3 100644
--- a/contracts/Storage.sol
+++ b/contracts/Storage.sol
@@ -45,7 +45,12 @@ contract Storage is Contracts, Proofs, Stakes {
     );
   }
 
-  function startContract(bytes32 id) public {
+  modifier onlyHost(bytes32 id) {
+    require(msg.sender == host(id), "Only host can call this function");
+    _;
+  }
+
+  function startContract(bytes32 id) public onlyHost(id) {
     _expectProofs(id, proofPeriod(id), proofTimeout(id), duration(id));
   }
 
diff --git a/test/Storage.test.js b/test/Storage.test.js
index e7850d0..6627e64 100644
--- a/test/Storage.test.js
+++ b/test/Storage.test.js
@@ -67,6 +67,12 @@ describe("Storage", function () {
         await storage.connect(host).startContract(id)
         expect(await storage.proofEnd(id)).to.be.gt(0)
       })
+
+      it("can only be done by the host", async function () {
+        await expect(
+          storage.connect(client).startContract(id)
+        ).to.be.revertedWith("Only host can call this function")
+      })
     })
   })