diff --git a/MantidQt/CustomInterfaces/inc/MantidQtCustomInterfaces/Tomography/StackOfImagesDirs.h b/MantidQt/CustomInterfaces/inc/MantidQtCustomInterfaces/Tomography/StackOfImagesDirs.h
index 98458140959fffc20cefefce946f9cf575fc72f1..3ef122016ea93de03b22395c15ab647d62ea9324 100644
--- a/MantidQt/CustomInterfaces/inc/MantidQtCustomInterfaces/Tomography/StackOfImagesDirs.h
+++ b/MantidQt/CustomInterfaces/inc/MantidQtCustomInterfaces/Tomography/StackOfImagesDirs.h
@@ -44,7 +44,7 @@ public:
   bool isValid() const { return m_valid; }
 
   // human readable description of the expected structure of directories
-  std::string description() const { return g_descr; }
+  std::string description() const;
 
   // string that describes the status/error message about this directory
   std::string status() const;
diff --git a/MantidQt/CustomInterfaces/src/Tomography/StackOfImagesDirs.cpp b/MantidQt/CustomInterfaces/src/Tomography/StackOfImagesDirs.cpp
index da61efebe8f948ee060d3709dcfe743871c0b526..d8be84c4a5db207fb1285d9888532c6e30c86fe3 100644
--- a/MantidQt/CustomInterfaces/src/Tomography/StackOfImagesDirs.cpp
+++ b/MantidQt/CustomInterfaces/src/Tomography/StackOfImagesDirs.cpp
@@ -25,6 +25,8 @@ StackOfImagesDirs::StackOfImagesDirs(const std::string &path)
   findStackDirs(path);
 }
 
+std::string StackOfImagesDirs::description() const { return g_descr; }
+
 std::string StackOfImagesDirs::status() const {
   if (m_valid)
     return "Stack of images is correct";