diff --git a/Code/Mantid/Framework/Algorithms/src/ReflectometryWorkflowBase.cpp b/Code/Mantid/Framework/Algorithms/src/ReflectometryWorkflowBase.cpp
index dd3945b6c7b5..8c15710f4bba 100644
--- a/Code/Mantid/Framework/Algorithms/src/ReflectometryWorkflowBase.cpp
+++ b/Code/Mantid/Framework/Algorithms/src/ReflectometryWorkflowBase.cpp
@@ -234,8 +234,18 @@ namespace Mantid
       // Verify that all the required inputs for the second transmission run are now given.
       if (isPropertyDefault("FirstTransmissionRun"))
       {
-        throw std::invalid_argument(
-            "A SecondTransmissionRun is only valid if a FirstTransmissionRun is provided.");
+        if (firstTransmissionInWavelength)
+        {
+          this->g_log.warning(
+              "The first transmission run is in wavelength so is assumed to be correctly stitched in wavelength. "
+                  "The second transmission run and associated inputs will be ignored."
+                  "Run CreateTransmissionWorkspace to create a transmission workspace from TOF runs.");
+        }
+        else
+        {
+          throw std::invalid_argument(
+                      "A SecondTransmissionRun is only valid if a FirstTransmissionRun is provided.");
+        }
       }  
       else
       {