diff --git a/src/sampling/probes/probes.C b/src/sampling/probes/probes.C
index cb21c6299c8da271edac454a650ce64b3745761f..8eee0048ca86bbb9047b71d16ab850db35a080f9 100644
--- a/src/sampling/probes/probes.C
+++ b/src/sampling/probes/probes.C
@@ -104,26 +104,11 @@ Foam::label Foam::probes::prepare()
     {
         wordHashSet currentFields;
 
-        forAll(scalarFields_, fieldI)
-        {
-            currentFields.set(scalarFields_[fieldI]);
-        }
-        forAll(vectorFields_, fieldI)
-        {
-            currentFields.set(vectorFields_[fieldI]);
-        }
-        forAll(sphericalTensorFields_, fieldI)
-        {
-            currentFields.set(sphericalTensorFields_[fieldI]);
-        }
-        forAll(symmTensorFields_, fieldI)
-        {
-            currentFields.set(symmTensorFields_[fieldI]);
-        }
-        forAll(tensorFields_, fieldI)
-        {
-            currentFields.set(tensorFields_[fieldI]);
-        }
+        currentFields.insert(scalarFields_);
+        currentFields.insert(vectorFields_);
+        currentFields.insert(sphericalTensorFields_);
+        currentFields.insert(symmTensorFields_);
+        currentFields.insert(tensorFields_);
 
         if (debug)
         {