diff --git a/src/analysis/typepal/Solver.rsc b/src/analysis/typepal/Solver.rsc
index 77bb0b0..e5bfe24 100644
--- a/src/analysis/typepal/Solver.rsc
+++ b/src/analysis/typepal/Solver.rsc
@@ -934,7 +934,7 @@ Solver newSolver(map[str,Tree] namedTrees, TModel tm){
     }
 
     bool unify(AType given, AType expected){
-        boolean ok = false;
+        bool ok = false;
         <ok, bindings1> = unify(given, expected, bindings);
         if(ok){
             bindings += bindings1;