diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 198c329d709..37698f0af5f 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -6213,7 +6213,7 @@ namespace ts {
             }
             if (source.symbol.name !== target.symbol.name ||
                 !(source.symbol.flags & SymbolFlags.RegularEnum) || !(target.symbol.flags & SymbolFlags.RegularEnum) ||
-                !(source.flags & TypeFlags.Union) || !(target.flags & TypeFlags.Union)) {
+                (source.flags & TypeFlags.Union) !== (target.flags & TypeFlags.Union)) {
                 return (enumRelation[id] = false);
             }
             const targetEnumType = getTypeOfSymbol(target.symbol);