diff --git a/parse.yy b/parse.yy
index 6ed2a43d..4b315776 100644
--- a/parse.yy
+++ b/parse.yy
@@ -2278,7 +2278,11 @@ lGetConstantInt(Expr *expr, int *value, SourcePos pos, const char *usage) {
             Error(pos, "%s must be representable with a 32-bit integer.", usage);
             return false;
         }
-        *value = (int)ci->getZExtValue();
+        const Type *type = expr->GetType();
+        if (type->IsUnsignedType())
+            *value = (int)ci->getZExtValue();
+        else
+            *value = (int)ci->getSExtValue();
         return true;
     }
 }