diff --git a/pkg/expr/commands_test.go b/pkg/expr/commands_test.go
index aa741dada2e..9109e6fc6ec 100644
--- a/pkg/expr/commands_test.go
+++ b/pkg/expr/commands_test.go
@@ -169,7 +169,7 @@ func TestReduceExecute(t *testing.T) {
 
 func randomReduceFunc() string {
 	res := mathexp.GetSupportedReduceFuncs()
-	return res[rand.Intn(len(res)-1)]
+	return res[rand.Intn(len(res))]
 }
 
 func TestResampleCommand_Execute(t *testing.T) {
diff --git a/pkg/services/ngalert/api/api_ruler_validation_test.go b/pkg/services/ngalert/api/api_ruler_validation_test.go
index b5098d167f4..00d76433882 100644
--- a/pkg/services/ngalert/api/api_ruler_validation_test.go
+++ b/pkg/services/ngalert/api/api_ruler_validation_test.go
@@ -69,8 +69,8 @@ func validRule() apimodels.PostableExtendedRuleNode {
 				},
 			},
 			UID:          util.GenerateShortUID(),
-			NoDataState:  allNoData[rand.Intn(len(allNoData)-1)],
-			ExecErrState: allExecError[rand.Intn(len(allExecError)-1)],
+			NoDataState:  allNoData[rand.Intn(len(allNoData))],
+			ExecErrState: allExecError[rand.Intn(len(allExecError))],
 		},
 	}
 }
diff --git a/pkg/services/ngalert/api/util_test.go b/pkg/services/ngalert/api/util_test.go
index 3ed32d797e6..ce79d0fed9f 100644
--- a/pkg/services/ngalert/api/util_test.go
+++ b/pkg/services/ngalert/api/util_test.go
@@ -163,14 +163,15 @@ func Test_containsProvisionedAlerts(t *testing.T) {
 	t.Run("should return true if at least one rule is provisioned", func(t *testing.T) {
 		_, rules := models2.GenerateUniqueAlertRules(rand.Intn(4)+2, models2.AlertRuleGen())
 		provenance := map[string]models2.Provenance{
-			rules[rand.Intn(len(rules)-1)].UID: []models2.Provenance{models2.ProvenanceAPI, models2.ProvenanceFile}[rand.Intn(2)],
+			rules[rand.Intn(len(rules))].UID: []models2.Provenance{models2.ProvenanceAPI, models2.ProvenanceFile}[rand.Intn(2)],
 		}
 		require.Truef(t, containsProvisionedAlerts(provenance, rules), "the group of rules is expected to be considered as provisioned but it isn't. Provenances: %v", provenance)
 	})
 	t.Run("should return false if map does not contain or has ProvenanceNone", func(t *testing.T) {
 		_, rules := models2.GenerateUniqueAlertRules(rand.Intn(5)+1, models2.AlertRuleGen())
 		provenance := make(map[string]models2.Provenance)
-		for i := 0; i < rand.Intn(len(rules)); i++ {
+		numProvenanceNone := rand.Intn(len(rules))
+		for i := 0; i < numProvenanceNone; i++ {
 			provenance[rules[i].UID] = models2.ProvenanceNone
 		}
 		require.Falsef(t, containsProvisionedAlerts(provenance, rules), "the group of rules is not expected to be provisioned but it is. Provenances: %v", provenance)
diff --git a/pkg/services/ngalert/models/testing.go b/pkg/services/ngalert/models/testing.go
index 82b0ab7d443..6c1ed0c7897 100644
--- a/pkg/services/ngalert/models/testing.go
+++ b/pkg/services/ngalert/models/testing.go
@@ -25,7 +25,7 @@ func AlertRuleGen(mutators ...AlertRuleMutator) func() *AlertRule {
 				NoData,
 				OK,
 			}
-			return s[rand.Intn(len(s)-1)]
+			return s[rand.Intn(len(s))]
 		}
 
 		randErrState := func() ExecutionErrorState {
@@ -34,7 +34,7 @@ func AlertRuleGen(mutators ...AlertRuleMutator) func() *AlertRule {
 				ErrorErrState,
 				OkErrState,
 			}
-			return s[rand.Intn(len(s)-1)]
+			return s[rand.Intn(len(s))]
 		}
 
 		interval := (rand.Int63n(6) + 1) * 10
diff --git a/pkg/services/ngalert/store/deltas_test.go b/pkg/services/ngalert/store/deltas_test.go
index 6f066d9907a..d3e63758e88 100644
--- a/pkg/services/ngalert/store/deltas_test.go
+++ b/pkg/services/ngalert/store/deltas_test.go
@@ -328,7 +328,7 @@ func TestCalculateAutomaticChanges(t *testing.T) {
 		group2 := models.GenerateGroupKey(orgID)
 		rules2 := models.GenerateAlertRules(4, models.AlertRuleGen(withGroupKey(group2), models.WithSequentialGroupIndex()))
 
-		movedIndex := rand.Intn(len(rules2) - 1)
+		movedIndex := rand.Intn(len(rules2))
 		movedRule := rules2[movedIndex]
 		copyRule := models.CopyRule(movedRule)
 		copyRule.RuleGroup = group.RuleGroup