diff --git a/Framework/Kernel/src/PropertyWithValue.cpp b/Framework/Kernel/src/PropertyWithValue.cpp
index ac21f2e46117e4d21756dc627ffacdfabc0c6901..d38595344765a0f0ab0c9462d40b0593e24c6651 100644
--- a/Framework/Kernel/src/PropertyWithValue.cpp
+++ b/Framework/Kernel/src/PropertyWithValue.cpp
@@ -34,7 +34,6 @@ PROPERTYWITHVALUE_SAVEPROPERTY(uint64_t)
 PROPERTYWITHVALUE_SAVEPROPERTY(std::string)
 PROPERTYWITHVALUE_SAVEPROPERTY(std::vector<double>)
 PROPERTYWITHVALUE_SAVEPROPERTY(std::vector<int32_t>)
-PROPERTYWITHVALUE_SAVEPROPERTY(std::vector<int64_t>)
 
 /// @cond
 template class MANTID_KERNEL_DLL PropertyWithValue<uint16_t>;
diff --git a/Framework/PythonInterface/plugins/algorithms/CropWorkspaceForMDNorm.py b/Framework/PythonInterface/plugins/algorithms/CropWorkspaceForMDNorm.py
index 8feb07972e8432eb2637ac93376fb74e9d6e6be2..c2345beb41cbf5de17a165d44f1278b00b8d1f95 100644
--- a/Framework/PythonInterface/plugins/algorithms/CropWorkspaceForMDNorm.py
+++ b/Framework/PythonInterface/plugins/algorithms/CropWorkspaceForMDNorm.py
@@ -110,7 +110,7 @@ class CropWorkspaceForMDNorm(PythonAlgorithm):
                 raise RuntimeError("Could not compare old and new values for 'MDNorm_high' log. "+
                                    "Make sure the length of the old data is equal to the number of spectra")
         run_obj.addProperty('MDNorm_high', [xmax]*num_spectra, True)
-        run_obj.addProperty('MDNorm_spectra_index', numpy.arange(num_spectra).tolist(), True)
+        run_obj.addProperty('MDNorm_spectra_index', numpy.arange(num_spectra, dtype=float).tolist(), True)
         self.setProperty('OutputWorkspace', out_ws)
 
 # Register algorithm with Mantid.