diff --git a/internal/consensus/common_test.go b/internal/consensus/common_test.go
index 4172d889c..7637a0fae 100644
--- a/internal/consensus/common_test.go
+++ b/internal/consensus/common_test.go
@@ -238,9 +238,9 @@ func decideProposal(
 ) (proposal *types.Proposal, block *types.Block) {
 	t.Helper()
 
-	cs1.mtx.Lock()
 	block, blockParts, err := cs1.createProposalBlock(ctx)
 	require.NoError(t, err)
+	cs1.mtx.Lock()
 	validRound := cs1.ValidRound
 	chainID := cs1.state.ChainID
 	cs1.mtx.Unlock()