diff --git a/src/A3t.cpp b/src/A3t.cpp
index c99566e53..8923b3fa5 100644
--- a/src/A3t.cpp
+++ b/src/A3t.cpp
@@ -552,8 +552,13 @@ void A3t::findAttribute ()
             (*i)->attribute ("name", canonical);
             (*i)->attribute ("value", value);
 
-            if (context.columns[canonical]->modifiable ())
+            std::map <std::string, Column*>::const_iterator col;
+            col = context.columns.find (canonical);
+            if (col != context.columns.end () &&
+                col->second->modifiable ())
+            {
               (*i)->tag ("MODIFIABLE");
+            }
           }
 
           else if (canonicalize (canonical, "uda", name))
diff --git a/src/columns/ColUDA.cpp b/src/columns/ColUDA.cpp
index becd41b3d..ac2dc47b6 100644
--- a/src/columns/ColUDA.cpp
+++ b/src/columns/ColUDA.cpp
@@ -43,6 +43,7 @@ ColumnUDA::ColumnUDA ()
   _type  = "string";
   _style = "default";
   _label = "";
+  _uda   = true;
 
   _hyphenate = (_type == "string") ? true : false;
 
@@ -56,12 +57,6 @@ ColumnUDA::~ColumnUDA ()
 {
 }
 
-////////////////////////////////////////////////////////////////////////////////
-bool ColumnUDA::is_uda () const
-{
-  return true;
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 bool ColumnUDA::validate (std::string& value)
 {
diff --git a/src/columns/ColUDA.h b/src/columns/ColUDA.h
index 4ab454553..196e0e91b 100644
--- a/src/columns/ColUDA.h
+++ b/src/columns/ColUDA.h
@@ -39,7 +39,6 @@ public:
   ColumnUDA ();
   ~ColumnUDA ();
 
-  bool is_uda () const;
   bool validate (std::string&);
   void measure (Task&, unsigned int&, unsigned int&);
   void render (std::vector <std::string>&, Task&, int, Color&);
diff --git a/src/columns/Column.cpp b/src/columns/Column.cpp
index 535bbb8e3..59330ea61 100644
--- a/src/columns/Column.cpp
+++ b/src/columns/Column.cpp
@@ -209,6 +209,7 @@ Column::Column ()
 , _label ("")
 , _report ("")
 , _modifiable (true)
+, _uda (false)
 {
 }
 
@@ -221,6 +222,7 @@ Column::Column (const Column& other)
   _label      = other._label;
   _label      = other._report;
   _modifiable = other._modifiable;
+  _uda        = other._uda;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -234,6 +236,7 @@ Column& Column::operator= (const Column& other)
     _label       = other._label;
     _report      = other._report;
     _modifiable  = other._modifiable;
+    _uda         = other._uda;
   }
 
   return *this;
@@ -242,12 +245,13 @@ Column& Column::operator= (const Column& other)
 ////////////////////////////////////////////////////////////////////////////////
 bool Column::operator== (const Column& other) const
 {
-  return _name       == other._name   &&
-         _type       == other._type   &&
-         _style      == other._style  &&
-         _label      == other._label  &&
-         _report     == other._report &&
-         _modifiable == other._modifiable;
+  return _name       == other._name       &&
+         _type       == other._type       &&
+         _style      == other._style      &&
+         _label      == other._label      &&
+         _report     == other._report     &&
+         _modifiable == other._modifiable &&
+         _uda        == other._uda;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/src/columns/Column.h b/src/columns/Column.h
index 91e77e885..d4cd95e3c 100644
--- a/src/columns/Column.h
+++ b/src/columns/Column.h
@@ -50,7 +50,7 @@ public:
   std::string label () const                  { return _label;      }
   std::string type () const                   { return _type;       }
   bool modifiable () const                    { return _modifiable; }
-  bool is_uda () const                        { return false;       }
+  bool is_uda () const                        { return _uda;        }
   std::vector <std::string> styles () const   { return _styles;     }
   std::vector <std::string> examples () const { return _examples;   }
 
@@ -74,6 +74,7 @@ protected:
   std::string _label;
   std::string _report;
   bool _modifiable;
+  bool _uda;
   std::vector <std::string> _styles;
   std::vector <std::string> _examples;
 };