diff --git a/src/ast/rewriter/bool_rewriter.cpp b/src/ast/rewriter/bool_rewriter.cpp
index 05f47ada7..f6597fbc5 100644
--- a/src/ast/rewriter/bool_rewriter.cpp
+++ b/src/ast/rewriter/bool_rewriter.cpp
@@ -59,9 +59,12 @@ br_status bool_rewriter::mk_app_core(func_decl * f, unsigned num_args, expr * co
         mk_implies(args[0], args[1], result);
         return BR_DONE;
     case OP_XOR:
-        SASSERT(num_args == 2);
-        mk_xor(args[0], args[1], result);
-        return BR_DONE;
+        switch (num_args) {
+        case 0: return BR_FAILED;
+        case 1: result = args[0]; return BR_DONE;
+        case 2: mk_xor(args[0], args[1], result); return BR_DONE;
+        default: UNREACHABLE(); return BR_FAILED;
+        }
     default:
         return BR_FAILED;
     }