diff --git a/question/q015.md b/question/q015.md
index b460d6a..f14a9d4 100644
--- a/question/q015.md
+++ b/question/q015.md
@@ -19,7 +19,7 @@ func main() {
 }
 func A() {
 	mu.Lock()
-	defer mu.Lock()
+	defer mu.Unlock()
 	chain = chain + " --> A"
 	B()
 }
@@ -29,7 +29,7 @@ func B() {
 }
 func C() {
 	mu.Lock()
-	defer mu.Lock()
+	defer mu.Unlock()
 	chain = chain + " --> C"
 }
 ```