diff --git a/lib/compress.js b/lib/compress.js
index ee255d78..c3b76118 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1446,7 +1446,7 @@ merge(Compressor.prototype, {
                 return make_node(AST_True, self);
             }
         }
-        if (e instanceof AST_Binary) {
+        if (e instanceof AST_Binary && self.operator == "!") {
             self = best_of(self, e.negate(compressor));
         }
         return self.evaluate(compressor)[0];