diff -r 0206df35882c -r c58dff4e560c jitcraft/SemanticAnalysis.cpp
--- a/jitcraft/SemanticAnalysis.cpp	Tue Jul 17 21:40:44 2012 -0700
+++ b/jitcraft/SemanticAnalysis.cpp	Tue Jul 17 23:05:38 2012 -0700
@@ -355,6 +355,14 @@
         node->setType(type);
         break;
 
+      case TOK_MINUS:
+        if (!type->isFloat() && (!type->isInt32() || type->tag())) {
+            unaryTypeError(node, node->token(), type);
+            return;
+        }
+        node->setType(type);
+        break;
+
       default:
         assert(node->token() == TOK_TILDE);
         if (!type->isInt32() || type->tag()) {