diff --git a/src/dynamicMesh/dynamicFvMesh/mixerGgiFvMesh/mixerGgiFvMesh.C b/src/dynamicMesh/dynamicFvMesh/mixerGgiFvMesh/mixerGgiFvMesh.C
index a320de585..f0562f8bc 100644
--- a/src/dynamicMesh/dynamicFvMesh/mixerGgiFvMesh/mixerGgiFvMesh.C
+++ b/src/dynamicMesh/dynamicFvMesh/mixerGgiFvMesh/mixerGgiFvMesh.C
@@ -138,8 +138,16 @@ void Foam::mixerGgiFvMesh::calcMovingMasks() const
     const cellList& c = cells();
     const faceList& f = allFaces();
 
-    const labelList& cellAddr =
-        cellZones()[cellZones().findZoneID("movingCells")];
+    label movingCellsID = cellZones().findZoneID("movingCells");
+
+    if (movingCellsID < 0)
+    {
+        FatalErrorIn("void mixerGgiFvMesh::calcMovingMasks() const")
+            << "Cannot find moving cell zone ID"
+            << abort(FatalError);
+    }
+
+    const labelList& cellAddr = cellZones()[movingCellsID];
 
     forAll (cellAddr, cellI)
     {
@@ -162,13 +170,10 @@ void Foam::mixerGgiFvMesh::calcMovingMasks() const
 
     forAll (movingPatches, patchI)
     {
-        polyPatchID movingSliderID
-        (
-            movingPatches[patchI],
-            boundaryMesh()
-        );
+        const label movingSliderID =
+            boundaryMesh().findPatchID(movingPatches[patchI]);
 
-        if (!movingSliderID.active())
+        if (movingSliderID < 0)
         {
             FatalErrorIn("void mixerGgiFvMesh::calcMovingMasks() const")
                 << "Moving slider named " << movingPatches[patchI]
@@ -177,7 +182,7 @@ void Foam::mixerGgiFvMesh::calcMovingMasks() const
         }
 
         const ggiPolyPatch& movingGgiPatch =
-            refCast<const ggiPolyPatch>(boundaryMesh()[movingSliderID.index()]);
+            refCast<const ggiPolyPatch>(boundaryMesh()[movingSliderID]);
 
         const labelList& movingSliderAddr = movingGgiPatch.zone();
 
@@ -197,13 +202,10 @@ void Foam::mixerGgiFvMesh::calcMovingMasks() const
 
     forAll (staticPatches, patchI)
     {
-        polyPatchID staticSliderID
-        (
-            staticPatches[patchI],
-            boundaryMesh()
-        );
+        const label staticSliderID =
+            boundaryMesh().findPatchID(movingPatches[patchI]);
 
-        if (!staticSliderID.active())
+        if (staticSliderID < 0)
         {
             FatalErrorIn("void mixerGgiFvMesh::calcMovingMasks() const")
                 << "Static slider named " << staticPatches[patchI]
@@ -212,7 +214,7 @@ void Foam::mixerGgiFvMesh::calcMovingMasks() const
         }
 
         const ggiPolyPatch& staticGgiPatch =
-            refCast<const ggiPolyPatch>(boundaryMesh()[staticSliderID.index()]);
+            refCast<const ggiPolyPatch>(boundaryMesh()[staticSliderID]);
 
         const labelList& staticSliderAddr = staticGgiPatch.zone();
 
diff --git a/src/dynamicMesh/topoChangerFvMesh/multiMixerFvMesh/mixerRotor.C b/src/dynamicMesh/topoChangerFvMesh/multiMixerFvMesh/mixerRotor.C
index a3197a2c4..503be205d 100644
--- a/src/dynamicMesh/topoChangerFvMesh/multiMixerFvMesh/mixerRotor.C
+++ b/src/dynamicMesh/topoChangerFvMesh/multiMixerFvMesh/mixerRotor.C
@@ -28,6 +28,7 @@ License
 #include "regionSplit.H"
 #include "polyTopoChanger.H"
 #include "slidingInterface.H"
+#include "ggiPolyPatch.H"
 #include "Time.H"
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
@@ -221,8 +222,17 @@ void Foam::mixerRotor::calcMovingMask() const
     const cellList& c = mesh_.cells();
     const faceList& f = mesh_.allFaces();
 
-    const labelList& cellAddr = mesh_.cellZones()
-        [mesh_.cellZones().findZoneID("movingCellsZone" + name_)];
+    label movingCellZoneID =
+        mesh_.cellZones().findZoneID("movingCellsZone" + name_);
+
+    if (movingCellZoneID < 0)
+    {
+        FatalErrorIn("void mixerRotor::calcMovingMask() const")
+            << "Cannot find moving cell zone ID"
+            << abort(FatalError);
+    }
+
+    const labelList& cellAddr = mesh_.cellZones()[movingCellZoneID];
 
     forAll (cellAddr, cellI)
     {
@@ -241,8 +251,35 @@ void Foam::mixerRotor::calcMovingMask() const
     }
 
     // Attempt to enforce motion on sliders if zones exist
-    const label msI =
-        mesh_.faceZones().findZoneID(movingSliderName_ + "Zone" + name_);
+
+    // Master side
+    label msI = -1;
+
+    if (useTopoSliding_)
+    {
+        // For topological changes, find the zone
+        msI = mesh_.faceZones().findZoneID(movingSliderName_ + "Zone" + name_);
+    }
+    else
+    {
+        // For GGI, take face zone from ggi interpolator
+        label movingSliderIndex =
+            mesh_.boundaryMesh().findPatchID(movingSliderName_);
+
+        if (movingSliderIndex > -1)
+        {
+            if (isA<ggiPolyPatch>(mesh_.boundaryMesh()[movingSliderIndex]))
+            {
+                const ggiPolyPatch& movingSliderGgi =
+                    refCast<const ggiPolyPatch>
+                    (
+                        mesh_.boundaryMesh()[movingSliderIndex]
+                    );
+
+                msI = mesh_.faceZones().findZoneID(movingSliderGgi.zoneName());
+            }
+        }
+    }
 
     if (msI > -1)
     {
@@ -259,8 +296,35 @@ void Foam::mixerRotor::calcMovingMask() const
         }
     }
 
-    const label ssI =
-        mesh_.faceZones().findZoneID(staticSliderName_ + "Zone" + name_);
+    // Slave side
+    label ssI = -1;
+
+    if (useTopoSliding_)
+    {
+        // For topological changes, find the zone
+        ssI = mesh_.faceZones().findZoneID(staticSliderName_ + "Zone" + name_);
+    }
+    else
+    {
+        // For GGI, take face zone from ggi interpolator
+        label staticSliderIndex =
+            mesh_.boundaryMesh().findPatchID(staticSliderName_);
+
+        if (staticSliderIndex > -1)
+        {
+            if (isA<ggiPolyPatch>(mesh_.boundaryMesh()[staticSliderIndex]))
+            {
+                const ggiPolyPatch& staticSliderGgi =
+                    refCast<const ggiPolyPatch>
+                    (
+                        mesh_.boundaryMesh()[staticSliderIndex]
+                    );
+
+                ssI = mesh_.faceZones().findZoneID(staticSliderGgi.zoneName());
+            }
+        }
+    }
+
 
     if (ssI > -1)
     {