diff --git a/Code/Mantid/Framework/PythonInterface/plugins/algorithms/WorkflowAlgorithms/MolDyn.py b/Code/Mantid/Framework/PythonInterface/plugins/algorithms/WorkflowAlgorithms/MolDyn.py
index 8e0165eaef88..ebce03896e89 100644
--- a/Code/Mantid/Framework/PythonInterface/plugins/algorithms/WorkflowAlgorithms/MolDyn.py
+++ b/Code/Mantid/Framework/PythonInterface/plugins/algorithms/WorkflowAlgorithms/MolDyn.py
@@ -75,7 +75,7 @@ def PyInit(self):
                              doc='Resolution workspace')
 
         self.declareProperty(name='MaxEnergy', defaultValue='',
-                             doc='Crop the result spectra at a given energy')
+                             doc='Crop the result spectra at a given energy (leave blank for no crop)')
 
         self.declareProperty(name='Plot', defaultValue='None',
                              validator=StringListValidator(['None', 'Spectra', 'Contour', 'Both']),
@@ -97,7 +97,7 @@ def validateInputs(self):
         sample_filename = self.getPropertyValue('Filename')
         function_list = self.getProperty('Functions').value
         res_ws = self.getPropertyValue('Resolution')
-        emax = self.getPropertyValue('MaxEnergy')
+        emax = self.getProperty('MaxEnergy')
 
         if len(function_list) == 0 and os.path.splitext(sample_filename)[1] == 'cdl':
             issues['Functions'] = 'Must specify at least one function when loading a CDL file'
diff --git a/Code/Mantid/MantidQt/CustomInterfaces/inc/MantidQtCustomInterfaces/IndirectMolDyn.ui b/Code/Mantid/MantidQt/CustomInterfaces/inc/MantidQtCustomInterfaces/IndirectMolDyn.ui
index 78d9746e8396..6326d471608d 100644
--- a/Code/Mantid/MantidQt/CustomInterfaces/inc/MantidQtCustomInterfaces/IndirectMolDyn.ui
+++ b/Code/Mantid/MantidQt/CustomInterfaces/inc/MantidQtCustomInterfaces/IndirectMolDyn.ui
@@ -104,19 +104,21 @@
          </spacer>
         </item>
         <item>
-         <widget class="QLineEdit" name="leMaxEnergy">
+         <widget class="QDoubleSpinBox" name="dspMaxEnergy">
+          <property name="minimumSize">
+           <size>
+            <width>150</width>
+            <height>0</height>
+           </size>
+          </property>
           <property name="toolTip">
-           <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;Crop the upper energy range of any workspaces with energy as the X unit (e.g. Sqw).&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+           <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;Crop the upper energy range of any workspaces with energy as the X unit (e.g. S(Q,w)).&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
           </property>
-          <property name="text">
-           <string>0</string>
+          <property name="suffix">
+           <string> meV</string>
           </property>
-         </widget>
-        </item>
-        <item>
-         <widget class="QLabel" name="lblEnergyCropUnits">
-          <property name="text">
-           <string>meV</string>
+          <property name="maximum">
+           <double>1000.000000000000000</double>
           </property>
          </widget>
         </item>
@@ -308,7 +310,7 @@
   <tabstop>mwRun</tabstop>
   <tabstop>leFunctionNames</tabstop>
   <tabstop>ckCropEnergy</tabstop>
-  <tabstop>leMaxEnergy</tabstop>
+  <tabstop>dspMaxEnergy</tabstop>
   <tabstop>ckResolution</tabstop>
   <tabstop>dsResolution</tabstop>
   <tabstop>ckVerbose</tabstop>
diff --git a/Code/Mantid/MantidQt/CustomInterfaces/src/IndirectMolDyn.cpp b/Code/Mantid/MantidQt/CustomInterfaces/src/IndirectMolDyn.cpp
index e82682d73410..003ddec59ed0 100644
--- a/Code/Mantid/MantidQt/CustomInterfaces/src/IndirectMolDyn.cpp
+++ b/Code/Mantid/MantidQt/CustomInterfaces/src/IndirectMolDyn.cpp
@@ -17,7 +17,7 @@ namespace MantidQt
       m_uiForm.setupUi(parent);
 
       connect(m_uiForm.ckResolution, SIGNAL(toggled(bool)), m_uiForm.dsResolution, SLOT(setEnabled(bool)));
-      connect(m_uiForm.ckCropEnergy, SIGNAL(toggled(bool)), m_uiForm.leMaxEnergy, SLOT(setEnabled(bool)));
+      connect(m_uiForm.ckCropEnergy, SIGNAL(toggled(bool)), m_uiForm.dspMaxEnergy, SLOT(setEnabled(bool)));
     }
 
     /**
@@ -50,14 +50,6 @@ namespace MantidQt
         return false;
       }
 
-      bool energyIsNumber = false;
-      m_uiForm.leMaxEnergy->text().toDouble(&energyIsNumber);
-      if(m_uiForm.ckCropEnergy->isChecked() && !energyIsNumber)
-      {
-        emit showMessageBox("Max energy must be a number.");
-        return false;
-      }
-
       return true;
     }
 
@@ -82,7 +74,7 @@ namespace MantidQt
 
       // Set energy crop option
       if(m_uiForm.ckCropEnergy->isChecked())
-        molDynAlg->setProperty("MaxEnergy", m_uiForm.leMaxEnergy->text().toStdString());
+        molDynAlg->setProperty("MaxEnergy", QString::number(m_uiForm.dspMaxEnergy->value()).toStdString());
 
       // Set instrument resolution option
       if(m_uiForm.ckResolution->isChecked())