diff --git a/.github/workflows/main-ci.yml b/.github/workflows/main-ci.yml
index b1b8a4c..cd4dddf 100644
--- a/.github/workflows/main-ci.yml
+++ b/.github/workflows/main-ci.yml
@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go-version: [1.12, 1.13, 1.14, ^1.14]
+        go-version: [1.12, 1.13, 1.14, 1.15, ^1.16]
     steps:
 
     - name: Set up Go 1.x
@@ -29,7 +29,7 @@ jobs:
         go get -v -t -d ./...
 
     - name: Run Tests
-      run: go test -v -cover ./...
+      run: go test -v -timeout 300s -cover ./...
     
     - name: Run Benchmarks
-      run: go test -bench=. -benchmem
+      run: go test -timeout 300s -bench=. -benchmem
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..01e4fbb
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,3 @@
+## v1.3.1
+
+- Fix `concurrent map read and map write` panic when accessing the map concurrently while getting an existing key, which is expired at the time. [#4]
\ No newline at end of file
diff --git a/timedmap.go b/timedmap.go
index e4ff8aa..9f81b12 100644
--- a/timedmap.go
+++ b/timedmap.go
@@ -228,6 +228,8 @@ func (tm *TimedMap) get(key interface{}, sec int) *element {
 	}
 
 	if time.Now().After(v.expires) {
+		tm.mtx.Lock()
+		defer tm.mtx.Unlock()
 		tm.expireElement(key, sec, v)
 		return nil
 	}
diff --git a/timedmap_test.go b/timedmap_test.go
index a15c202..45b4ad3 100644
--- a/timedmap_test.go
+++ b/timedmap_test.go
@@ -1,6 +1,7 @@
 package timedmap
 
 import (
+	"sync"
 	"testing"
 	"time"
 )
@@ -275,6 +276,27 @@ func TestConcurrentReadWrite(t *testing.T) {
 	time.Sleep(1 * time.Second)
 }
 
+func TestGetExpiredConcurrent(t *testing.T) {
+	tm := New(dCleanupTick)
+
+	wg := sync.WaitGroup{}
+	for i := 0; i < 50000; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			tm.Set(1, 1, 0)
+		}()
+
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			tm.GetValue(1)
+		}()
+	}
+
+	wg.Wait()
+}
+
 func TestExternalTicker(t *testing.T) {
 	const key = "tKeySet"
 	const val = "tValSet"