diff --git a/cluster-autoscaler/cloudprovider/gce/gce_manager.go b/cluster-autoscaler/cloudprovider/gce/gce_manager.go
index 946bd714b68a..7166bf4937ba 100644
--- a/cluster-autoscaler/cloudprovider/gce/gce_manager.go
+++ b/cluster-autoscaler/cloudprovider/gce/gce_manager.go
@@ -851,18 +851,16 @@ func (m *gceManagerImpl) forceRefresh() error {
 	return nil
 }
 
+// Fetch explicitly configured MIGs. These MIGs should never be unregistered
+// during refreshes, even if they no longer exist in GCE.
 func (m *gceManagerImpl) fetchExplicitMigs(specs []string) error {
 	m.assertGCE()
 
 	changed := false
-	for _, s := range specs {
-		spec, err := dynamic.SpecFromString(s, scaleToZeroSupported)
+	for _, spec := range specs {
+		mig, err := m.buildMigFromSpec(spec)
 		if err != nil {
-			return fmt.Errorf("failed to parse node group spec: %v", err)
-		}
-		mig := &Mig{gceManager: m, minSize: spec.MinSize, maxSize: spec.MaxSize, exist: true}
-		if mig.Project, mig.Zone, mig.Name, err = ParseMigUrl(spec.Name); err != nil {
-			return fmt.Errorf("failed to parse mig url: %s got error: %v", spec.Name, err)
+			return err
 		}
 		if m.RegisterMig(mig) {
 			changed = true
@@ -878,6 +876,20 @@ func (m *gceManagerImpl) fetchExplicitMigs(specs []string) error {
 	return nil
 }
 
+func (m *gceManagerImpl) buildMigFromSpec(spec string) (*Mig, error) {
+	s, err := dynamic.SpecFromString(spec, scaleToZeroSupported)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse node group spec: %v", err)
+	}
+	mig := &Mig{gceManager: m, minSize: s.MinSize, maxSize: s.MaxSize, exist: true}
+	if mig.Project, mig.Zone, mig.Name, err = ParseMigUrl(s.Name); err != nil {
+		return nil, fmt.Errorf("failed to parse mig url: %s got error: %v", s.Name, err)
+	}
+	return mig, nil
+}
+
+// Fetch automatically discovered MIGs. These MIGs should be unregistered if
+// they no longer exist in GCE.
 func (m *gceManagerImpl) fetchAutoMigs() error {
 	m.assertGCE()
 
@@ -889,18 +901,9 @@ func (m *gceManagerImpl) fetchAutoMigs() error {
 			return fmt.Errorf("cannot autodiscover managed instance groups: %s", err)
 		}
 		for _, link := range links {
-			spec := dynamic.NodeGroupSpec{
-				Name:               link,
-				MinSize:            cfg.MinSize,
-				MaxSize:            cfg.MaxSize,
-				SupportScaleToZero: scaleToZeroSupported,
-			}
-			if verr := spec.Validate(); verr != nil {
-				return fmt.Errorf("failed to create node group spec: %v", verr)
-			}
-			mig := &Mig{gceManager: m, minSize: spec.MinSize, maxSize: spec.MaxSize, exist: true}
-			if mig.Project, mig.Zone, mig.Name, err = ParseMigUrl(spec.Name); err != nil {
-				return fmt.Errorf("failed to parse mig url: %s got error: %v", spec.Name, err)
+			mig, err := m.buildMigFromAutoCfg(link, cfg)
+			if err != nil {
+				return err
 			}
 			if m.RegisterMig(mig) {
 				changed = true
@@ -925,6 +928,24 @@ func (m *gceManagerImpl) fetchAutoMigs() error {
 	return nil
 }
 
+func (m *gceManagerImpl) buildMigFromAutoCfg(link string, cfg cloudprovider.MIGAutoDiscoveryConfig) (*Mig, error) {
+	spec := dynamic.NodeGroupSpec{
+		Name:               link,
+		MinSize:            cfg.MinSize,
+		MaxSize:            cfg.MaxSize,
+		SupportScaleToZero: scaleToZeroSupported,
+	}
+	if verr := spec.Validate(); verr != nil {
+		return nil, fmt.Errorf("failed to create node group spec: %v", verr)
+	}
+	mig := &Mig{gceManager: m, minSize: spec.MinSize, maxSize: spec.MaxSize, exist: true}
+	var err error
+	if mig.Project, mig.Zone, mig.Name, err = ParseMigUrl(spec.Name); err != nil {
+		return nil, fmt.Errorf("failed to parse mig url: %s got error: %v", spec.Name, err)
+	}
+	return mig, nil
+}
+
 func (m *gceManagerImpl) fetchResourceLimiter() error {
 	m.assertGKENAP()