diff --git a/pkg/services/ngalert/state/manager.go b/pkg/services/ngalert/state/manager.go
index c55437c8502..d081614fd1a 100644
--- a/pkg/services/ngalert/state/manager.go
+++ b/pkg/services/ngalert/state/manager.go
@@ -557,6 +557,10 @@ func (st *Manager) processMissingSeriesStates(logger log.Logger, evaluatedAt tim
 			}
 
 			staleStatesCount++
+		} else if s.State == eval.Alerting {
+			// We need to update EndsAt for the state so that it will not be resolved by the
+			// Alertmanager automatically.
+			s.Maintain(alertRule.IntervalSeconds, evaluatedAt)
 		}
 
 		record := StateTransition{
diff --git a/pkg/services/ngalert/state/manager_private_test.go b/pkg/services/ngalert/state/manager_private_test.go
index e4ee2a27422..45ffba11fff 100644
--- a/pkg/services/ngalert/state/manager_private_test.go
+++ b/pkg/services/ngalert/state/manager_private_test.go
@@ -671,7 +671,7 @@ func TestProcessEvalResults_StateTransitions(t *testing.T) {
 							State:              eval.Alerting,
 							LatestResult:       newEvaluation(t1, eval.Alerting),
 							StartsAt:           t1,
-							EndsAt:             t1.Add(ResendDelay * 4),
+							EndsAt:             t2.Add(ResendDelay * 4),
 							LastEvaluationTime: t1,
 							LastSentAt:         &t1,
 						},
@@ -1037,7 +1037,7 @@ func TestProcessEvalResults_StateTransitions(t *testing.T) {
 							State:              eval.Alerting,
 							LatestResult:       newEvaluation(t1, eval.Alerting),
 							StartsAt:           t1,
-							EndsAt:             t1.Add(ResendDelay * 4),
+							EndsAt:             t2.Add(ResendDelay * 4),
 							LastEvaluationTime: t1,
 							LastSentAt:         &t1,
 						},
@@ -1113,7 +1113,7 @@ func TestProcessEvalResults_StateTransitions(t *testing.T) {
 							State:              eval.Alerting,
 							LatestResult:       newEvaluation(t1, eval.Alerting),
 							StartsAt:           t1,
-							EndsAt:             t1.Add(ResendDelay * 4),
+							EndsAt:             t3.Add(ResendDelay * 4),
 							LastEvaluationTime: t1,
 							LastSentAt:         &t1,
 						},
@@ -1647,7 +1647,7 @@ func TestProcessEvalResults_StateTransitions(t *testing.T) {
 									State:              eval.Alerting,
 									LatestResult:       newEvaluation(t1, eval.Alerting),
 									StartsAt:           t1,
-									EndsAt:             t1.Add(ResendDelay * 4),
+									EndsAt:             t2.Add(ResendDelay * 4),
 									LastEvaluationTime: t1,
 									LastSentAt:         &t1,
 									EvaluationDuration: time.Millisecond * 10,
@@ -2327,7 +2327,7 @@ func TestProcessEvalResults_StateTransitions(t *testing.T) {
 									State:              eval.Alerting,
 									LatestResult:       newEvaluation(t1, eval.Alerting),
 									StartsAt:           t1,
-									EndsAt:             t1.Add(ResendDelay * 4),
+									EndsAt:             t2.Add(ResendDelay * 4),
 									LastEvaluationTime: t1,
 									LastSentAt:         &t1,
 									EvaluationDuration: time.Millisecond * 10,
@@ -3063,7 +3063,7 @@ func TestProcessEvalResults_StateTransitions(t *testing.T) {
 									State:              eval.Alerting,
 									LatestResult:       newEvaluation(t1, eval.Alerting),
 									StartsAt:           t1,
-									EndsAt:             t1.Add(ResendDelay * 4),
+									EndsAt:             t2.Add(ResendDelay * 4),
 									LastEvaluationTime: t1,
 									LastSentAt:         &t1,
 									EvaluationDuration: time.Millisecond * 10,