diff --git a/nitro/state.nim b/nitro/state.nim
index 7e43be5..93ae98d 100644
--- a/nitro/state.nim
+++ b/nitro/state.nim
@@ -44,9 +44,11 @@ proc variablePart*(state: State): VariablePart =
 
 proc hashAppPart*(state: State): array[32, byte] =
   var writer: AbiWriter
+  writer.startTuple()
   writer.write(state.challengeDuration)
   writer.write(state.appDefinition)
   writer.write(state.appData)
+  writer.finishTuple()
   keccak256.digest(writer.finish).data
 
 proc hashState*(state: State): array[32, byte] =
diff --git a/tests/nitro/testState.nim b/tests/nitro/testState.nim
index eb8cca7..054163b 100644
--- a/tests/nitro/testState.nim
+++ b/tests/nitro/testState.nim
@@ -26,9 +26,11 @@ suite "state":
 
   test "hashes app part of state":
     var writer: AbiWriter
+    writer.startTuple()
     writer.write(state.challengeDuration)
     writer.write(state.appDefinition)
     writer.write(state.appData)
+    writer.finishTuple()
     let encoded = writer.finish()
     let hashed = keccak256.digest(encoded).data
     check hashAppPart(state) == hashed