diff --git a/mq/lib.go b/mq/lib.go
index 4686a21..f93bda3 100644
--- a/mq/lib.go
+++ b/mq/lib.go
@@ -73,6 +73,7 @@ type state[T any] struct {
 func (s *state[T]) Close() {
 	s.mu.Lock()
 	if s.closed {
+		s.mu.Unlock()
 		panic("close of closed queue")
 	}
 	s.closed = true
diff --git a/npq/lib.go b/npq/lib.go
index 6496397..2e0d79f 100644
--- a/npq/lib.go
+++ b/npq/lib.go
@@ -93,6 +93,7 @@ type state[P constraints.Integer, T any] struct {
 func (s *state[P, T]) Close() {
 	s.mu.Lock()
 	if s.closed {
+		s.mu.Unlock()
 		panic("close of closed queue")
 	}
 	s.closed = true
diff --git a/pq/lib.go b/pq/lib.go
index d69dcf5..8f45a8f 100644
--- a/pq/lib.go
+++ b/pq/lib.go
@@ -61,6 +61,7 @@ type state[P constraints.Ordered, T any] struct {
 func (s *state[P, T]) Close() {
 	s.mu.Lock()
 	if s.closed {
+		s.mu.Unlock()
 		panic("close of closed queue")
 	}
 	s.closed = true