diff --git a/src/Swarm/Game/Step.hs b/src/Swarm/Game/Step.hs
index 2d633f461..e80a24c74 100644
--- a/src/Swarm/Game/Step.hs
+++ b/src/Swarm/Game/Step.hs
@@ -1370,7 +1370,7 @@ execConst c vs s k = do
       [VBool b] -> return $ Out (VBool (not b)) s k
       _ -> badConst
     Neg -> case vs of
-      [VInt n] -> return $ Out (VInt (-n)) s k
+      [VInt n] -> return $ Out (VInt (- n)) s k
       _ -> badConst
     Eq -> returnEvalCmp
     Neq -> returnEvalCmp