diff --git a/applications/test/ListOps/Test-ListOps.C b/applications/test/ListOps/Test-ListOps.C
index 2efba98c7f..e722ced197 100644
--- a/applications/test/ListOps/Test-ListOps.C
+++ b/applications/test/ListOps/Test-ListOps.C
@@ -113,9 +113,9 @@ int main(int argc, char *argv[])
 
     Info<< nl << "Test lambda predicates:" << nl << endl;
 
-    List<label> test6(identity(19));
+    List<label> test6(identity(11));
     // shift range for general testing
-    std::for_each(test6.begin(), test6.end(), [](label& x){ x -= 10; });
+    std::for_each(test6.begin(), test6.end(), [](label& x){ x -= 4; });
 
     Info<< "Subset of non-zero, even values: "
         << subsetList
@@ -125,6 +125,16 @@ int main(int argc, char *argv[])
            ) << nl
         << endl;
 
+
+    test6.append(identity(13));
+
+    // Randomize the list
+    std::random_shuffle(test6.begin(), test6.end());
+
+    Info<< "Randomized: " << flatOutput(test6) << endl;
+    inplaceUniqueSort(test6);
+    Info<< "Unique    : " << flatOutput(test6) << endl;
+
     Info<< "\nEnd\n" << endl;
 
     return 0;
diff --git a/src/OpenFOAM/containers/Lists/ListOps/ListOps.H b/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
index 0c56f43cf5..441c785408 100644
--- a/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
+++ b/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
@@ -114,6 +114,17 @@ template<class T, class Cmp>
 void uniqueOrder(const UList<T>& lst, labelList& order, const Cmp& cmp);
 
 
+//- Inplace sorting and removal of duplicates.
+//  Do not use FixedList for the input list, since it doesn't resize.
+template<class ListType>
+void inplaceUniqueSort(ListType& lst);
+
+//- Inplace sorting and removal of duplicates.
+//  Do not use FixedList for the input list, since it doesn't resize.
+template<class ListType, class Cmp>
+void inplaceUniqueSort(ListType& lst, const Cmp& cmp);
+
+
 //- Extract elements of List when select is a certain value.
 //  \deprecated use subsetList instead (deprecated Mar 2017)
 template<class T, class ListType>
diff --git a/src/OpenFOAM/containers/Lists/ListOps/ListOpsTemplates.C b/src/OpenFOAM/containers/Lists/ListOps/ListOpsTemplates.C
index 69dbca60ec..9267221e99 100644
--- a/src/OpenFOAM/containers/Lists/ListOps/ListOpsTemplates.C
+++ b/src/OpenFOAM/containers/Lists/ListOps/ListOpsTemplates.C
@@ -227,8 +227,9 @@ void Foam::duplicateOrder
 
     sortedOrder(lst, order, cmp);
 
+    const label last = (order.size()-1);
     label n = 0;
-    for (label i = 0; i < order.size() - 1; ++i)
+    for (label i = 0; i < last; ++i)
     {
         if (lst[order[i]] == lst[order[i+1]])
         {
@@ -262,20 +263,50 @@ void Foam::uniqueOrder
 
     if (order.size() > 1)
     {
+        const label last = (order.size()-1);
         label n = 0;
-        for (label i = 0; i < order.size() - 1; ++i)
+        for (label i = 0; i < last; ++i)
         {
             if (lst[order[i]] != lst[order[i+1]])
             {
                 order[n++] = order[i];
             }
         }
-        order[n++] = order[order.size()-1];
+        order[n++] = order[last];
         order.setSize(n);
     }
 }
 
 
+template<class ListType>
+void Foam::inplaceUniqueSort(ListType& lst)
+{
+    inplaceUniqueSort
+    (
+        lst,
+        typename UList<typename ListType::value_type>::less(lst)
+    );
+}
+
+
+template<class ListType, class Cmp>
+void Foam::inplaceUniqueSort(ListType& lst, const Cmp& cmp)
+{
+    labelList order;
+    uniqueOrder(lst, order, cmp);
+
+    ListType newLst(order.size());
+    newLst.setSize(order.size()); // Consistent sizing (eg, DynamicList)
+
+    forAll(order, elemI)
+    {
+        newLst[elemI] = lst[order[elemI]];
+    }
+
+    lst.transfer(newLst);
+}
+
+
 template<class T, class ListType>
 ListType Foam::subset
 (