diff --git a/internal/internal_worker.go b/internal/internal_worker.go
index 76885b413..ebe658b51 100644
--- a/internal/internal_worker.go
+++ b/internal/internal_worker.go
@@ -700,6 +700,21 @@ func (r *registry) RegisterWorkflowWithOptions(
 	if len(alias) > 0 && r.workflowAliasMap != nil {
 		r.workflowAliasMap[fnName] = alias
 	}
+
+	if r.workflowAliasMap != nil {
+		// If workflowAliasMap[f] = a and workflowFuncMap[f] exists, invoking "f" will actually trigger workflowFuncMap[a].
+		// Unfortunately this is expected behavior when the user disobeys us by not turning on DisableRegistrationAliasing;
+		// see TestAliasStringNameClash, TestAliasUnqualifiedNameClash, and TestAliasAntialiasing. At least we can warn them.
+		a, ok1 := r.workflowAliasMap[fnName]
+		_, ok2 := r.workflowFuncMap[fnName]
+		if ok1 && ok2 {
+			fmt.Printf("WARNING: Workflow alias collision detected: invoking workflow \"%v\" will actually trigger \"%v\". Consider turning on 'WorkerOptions.DisableRegistrationAliasing'.\n", fnName, a)
+		}
+		a, ok3 := r.workflowAliasMap[registerName]
+		if ok3 {
+			fmt.Printf("WARNING: Workflow alias collision detected: invoking workflow \"%v\" will actually trigger \"%v\". Consider turning on 'WorkerOptions.DisableRegistrationAliasing'.\n", registerName, a)
+		}
+	}
 }
 
 func (r *registry) RegisterDynamicWorkflow(wf interface{}, options DynamicRegisterWorkflowOptions) {
@@ -780,6 +795,21 @@ func (r *registry) RegisterActivityWithOptions(
 	if len(alias) > 0 && r.activityAliasMap != nil {
 		r.activityAliasMap[fnName] = alias
 	}
+
+	if r.activityAliasMap != nil {
+		// If activityAliasMap[f] = a and activityFuncMap[f] exists, invoking "f" will actually trigger activityFuncMap[a].
+		// Unfortunately this is expected behavior when the user disobeys us by not turning on DisableRegistrationAliasing;
+		// see TestAliasStringNameClash, TestAliasUnqualifiedNameClash, and TestAliasAntialiasing. At least we can warn them.
+		a, ok1 := r.activityAliasMap[fnName]
+		_, ok2 := r.activityFuncMap[fnName]
+		if ok1 && ok2 {
+			fmt.Printf("WARNING: Activity alias collision detected: invoking activity \"%v\" will actually trigger \"%v\". Consider turning on 'WorkerOptions.DisableRegistrationAliasing'.\n", fnName, a)
+		}
+		a, ok3 := r.activityAliasMap[registerName]
+		if ok3 {
+			fmt.Printf("WARNING: Activity alias collision detected: invoking activity \"%v\" will actually trigger \"%v\". Consider turning on 'WorkerOptions.DisableRegistrationAliasing'.\n", registerName, a)
+		}
+	}
 }
 
 func (r *registry) registerActivityStructWithOptions(aStruct interface{}, options RegisterActivityOptions) error {
diff --git a/internal/internal_worker_test.go b/internal/internal_worker_test.go
index c08bb1aea..aa5e900c2 100644
--- a/internal/internal_worker_test.go
+++ b/internal/internal_worker_test.go
@@ -3384,6 +3384,45 @@ func TestAliasUnqualifiedNameClash(t *testing.T) {
 	require.Equal(t, "func1", executeWorkflow(true))
 }
 
+type aliasReproV1 struct{}
+func (aliasReproV1) MyActivity(context.Context) (string, error) { return "func1", nil }
+type aliasReproV2 struct{}
+func (aliasReproV2) MyActivity(context.Context) (string, error) { return "func2", nil }
+
+func TestAliasAntialiasing(t *testing.T) {
+	w := func(ctx Context) (string, error) {
+		ctx = WithActivityOptions(ctx, ActivityOptions{ScheduleToCloseTimeout: 5 * time.Second})
+		var str1 string
+		if err := ExecuteActivity(ctx, "MyActivity").Get(ctx, &str1); err != nil {
+			return "", err
+		}
+		var str2 string
+		if err := ExecuteActivity(ctx, "MyActivity_v2").Get(ctx, &str2); err != nil {
+			return "", err
+		}
+		return str1 + "-" + str2, nil
+	}
+
+	executeWorkflow := func(disableAlias bool) (result string) {
+		var suite WorkflowTestSuite
+		suite.SetDisableRegistrationAliasing(disableAlias)
+		env := suite.NewTestWorkflowEnvironment()
+		env.RegisterActivity(aliasReproV1{}.MyActivity)
+		env.RegisterActivityWithOptions(
+			aliasReproV2{}.MyActivity,
+			RegisterActivityOptions{Name: "MyActivity_v2"},
+		)
+		env.ExecuteWorkflow(w)
+		require.NoError(t, env.GetWorkflowResult(&result))
+		return
+	}
+
+	// Without disabling alias registration, the alias will choose aliasReproV2 both times.
+	// With disabling alias, we can disambiguate them properly.
+	require.Equal(t, "func2-func2", executeWorkflow(false))
+	require.Equal(t, "func1-func2", executeWorkflow(true))
+}
+
 func (s *internalWorkerTestSuite) TestReservedTemporalName() {
 	// workflow
 	worker := createWorker(s.service)
diff --git a/internal/worker.go b/internal/worker.go
index b93eec33d..acf86b463 100644
--- a/internal/worker.go
+++ b/internal/worker.go
@@ -326,8 +326,7 @@ type (
 		// Users are strongly recommended to set this as true if they register any
 		// workflow or activity functions with custom names. By leaving this as
 		// false, the historical default, ambiguity can occur between function names
-		// and aliased names when not using string names when executing child
-		// workflow or activities.
+		// and aliased names.
 		DisableRegistrationAliasing bool
 
 		// Assign a BuildID to this worker. This replaces the deprecated binary checksum concept,