diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 0ca3136e5f9..7d15aa64b8c 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -10619,7 +10619,7 @@ namespace ts {
                 target.flags & TypeFlags.Union ? some((<UnionType>target).types, t => isTypeDerivedFrom(source, t)) :
                 source.flags & TypeFlags.InstantiableNonPrimitive ? isTypeDerivedFrom(getBaseConstraintOfType(source) || emptyObjectType, target) :
                 target === globalObjectType ? !!(source.flags & (TypeFlags.Object | TypeFlags.NonPrimitive)) :
-                target === globalFunctionType ? isFunctionObjectType(source as ObjectType) :
+                target === globalFunctionType ? !!(source.flags & TypeFlags.Object) && isFunctionObjectType(source as ObjectType) :
                 hasBaseType(source, getTargetType(target));
             }