diff --git a/source/blender/blenkernel/BKE_material.hh b/source/blender/blenkernel/BKE_material.hh
index 01866dff9a4..34be7392e74 100644
--- a/source/blender/blenkernel/BKE_material.hh
+++ b/source/blender/blenkernel/BKE_material.hh
@@ -95,7 +95,11 @@ void BKE_object_material_array_assign(
     Main *bmain, Object *ob, Material ***matar, int totcol, bool to_object_only);
 
 short BKE_object_material_slot_find_index(Object *ob, Material *ma);
-bool BKE_object_material_slot_add(Main *bmain, Object *ob);
+/**
+ * \param set_active: Set the newly added slot as active material slot of the object. Usually that
+ * is wanted when adding a material slot, so it's the default.
+ */
+bool BKE_object_material_slot_add(Main *bmain, Object *ob, bool set_active = true);
 bool BKE_object_material_slot_remove(Main *bmain, Object *ob);
 bool BKE_object_material_slot_used(Object *object, short actcol);
 
diff --git a/source/blender/blenkernel/intern/grease_pencil.cc b/source/blender/blenkernel/intern/grease_pencil.cc
index a19074ff59b..3df78387948 100644
--- a/source/blender/blenkernel/intern/grease_pencil.cc
+++ b/source/blender/blenkernel/intern/grease_pencil.cc
@@ -2441,7 +2441,11 @@ Material *BKE_grease_pencil_object_material_ensure_from_brush(Main *bmain,
 
     /* check if the material is already on object material slots and add it if missing */
     if (ma && BKE_object_material_index_get(ob, ma) < 0) {
-      BKE_object_material_slot_add(bmain, ob);
+      /* The object's active material is what's used for the unpinned material. Do not touch it
+       * while using a pinned material. */
+      const bool change_active_material = false;
+
+      BKE_object_material_slot_add(bmain, ob, change_active_material);
       BKE_object_material_assign(bmain, ob, ma, ob->totcol, BKE_MAT_ASSIGN_USERPREF);
     }
 
diff --git a/source/blender/blenkernel/intern/material.cc b/source/blender/blenkernel/intern/material.cc
index 3250f472082..bf976f4a53a 100644
--- a/source/blender/blenkernel/intern/material.cc
+++ b/source/blender/blenkernel/intern/material.cc
@@ -1322,7 +1322,7 @@ short BKE_object_material_slot_find_index(Object *ob, Material *ma)
   return 0;
 }
 
-bool BKE_object_material_slot_add(Main *bmain, Object *ob)
+bool BKE_object_material_slot_add(Main *bmain, Object *ob, const bool set_active)
 {
   if (ob == nullptr) {
     return false;
@@ -1332,7 +1332,9 @@ bool BKE_object_material_slot_add(Main *bmain, Object *ob)
   }
 
   BKE_object_material_assign(bmain, ob, nullptr, ob->totcol + 1, BKE_MAT_ASSIGN_USERPREF);
-  ob->actcol = ob->totcol;
+  if (set_active) {
+    ob->actcol = ob->totcol;
+  }
   return true;
 }