diff --git a/pkg/services/ngalert/models/image.go b/pkg/services/ngalert/models/image.go
index 8c2d8cefd05..07c8578cdd9 100644
--- a/pkg/services/ngalert/models/image.go
+++ b/pkg/services/ngalert/models/image.go
@@ -27,7 +27,7 @@ func (i *Image) ExtendDuration(d time.Duration) {
 
 // HasExpired returns true if the image has expired.
 func (i *Image) HasExpired() bool {
-	return time.Now().After(i.ExpiresAt)
+	return timeNow().After(i.ExpiresAt)
 }
 
 // HasPath returns true if the image has a path on disk.
diff --git a/pkg/services/ngalert/models/image_test.go b/pkg/services/ngalert/models/image_test.go
index 5c8380cff04..7f9177fa8d6 100644
--- a/pkg/services/ngalert/models/image_test.go
+++ b/pkg/services/ngalert/models/image_test.go
@@ -4,6 +4,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/benbjohnson/clock"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -20,12 +21,18 @@ func TestImage_ExtendDuration(t *testing.T) {
 }
 
 func TestImage_HasExpired(t *testing.T) {
+	oldTimeNow := timeNow
+	timeNow = clock.NewMock().Now
+	t.Cleanup(func() {
+		timeNow = oldTimeNow
+	})
+
 	var i Image
-	i.ExpiresAt = time.Now().Add(time.Minute)
+	i.ExpiresAt = timeNow().Add(time.Minute)
 	assert.False(t, i.HasExpired())
-	i.ExpiresAt = time.Now()
-	assert.True(t, i.HasExpired())
-	i.ExpiresAt = time.Now().Add(-time.Minute)
+	i.ExpiresAt = timeNow()
+	assert.False(t, i.HasExpired())
+	i.ExpiresAt = timeNow().Add(-time.Minute)
 	assert.True(t, i.HasExpired())
 }
 
diff --git a/pkg/services/ngalert/models/time.go b/pkg/services/ngalert/models/time.go
new file mode 100644
index 00000000000..4e7b1a91163
--- /dev/null
+++ b/pkg/services/ngalert/models/time.go
@@ -0,0 +1,8 @@
+package models
+
+import "time"
+
+var (
+	// timeNow is an equivalent time.Now() that can be replaced in tests
+	timeNow = time.Now
+)