diff --git a/src/columns/ColTypeDate.cpp b/src/columns/ColTypeDate.cpp
index 357c9d6ce..869f94483 100644
--- a/src/columns/ColTypeDate.cpp
+++ b/src/columns/ColTypeDate.cpp
@@ -204,6 +204,12 @@ void ColumnTypeDate::render (
   }
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnTypeDate::validate (const std::string& input) const
+{
+  return input.length () ? true : false;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 void ColumnTypeDate::modify (Task& task, const std::string& value)
 {
diff --git a/src/columns/ColTypeDate.h b/src/columns/ColTypeDate.h
index 789339c04..fff7aecc1 100644
--- a/src/columns/ColTypeDate.h
+++ b/src/columns/ColTypeDate.h
@@ -39,6 +39,7 @@ public:
   ColumnTypeDate ();
   virtual void measure (Task&, unsigned int&, unsigned int&);
   virtual void render (std::vector <std::string>&, Task&, int, Color&);
+  virtual bool validate (const std::string&) const;
   virtual void modify (Task&, const std::string&);
 };
 
diff --git a/src/columns/ColTypeDuration.cpp b/src/columns/ColTypeDuration.cpp
index b3e433d81..144c95794 100644
--- a/src/columns/ColTypeDuration.cpp
+++ b/src/columns/ColTypeDuration.cpp
@@ -43,6 +43,12 @@ ColumnTypeDuration::ColumnTypeDuration ()
   _type = "duration";
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnTypeDuration::validate (const std::string& input) const
+{
+  return input.length () ? true : false;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 void ColumnTypeDuration::modify (Task& task, const std::string& value)
 {
diff --git a/src/columns/ColTypeDuration.h b/src/columns/ColTypeDuration.h
index d556a486c..54ab03c0a 100644
--- a/src/columns/ColTypeDuration.h
+++ b/src/columns/ColTypeDuration.h
@@ -35,6 +35,7 @@ class ColumnTypeDuration : public Column
 {
 public:
   ColumnTypeDuration ();
+  virtual bool validate (const std::string&) const;
   virtual void modify (Task&, const std::string&);
 };
 
diff --git a/src/columns/ColTypeNumeric.cpp b/src/columns/ColTypeNumeric.cpp
index b69147f1f..1f37cf382 100644
--- a/src/columns/ColTypeNumeric.cpp
+++ b/src/columns/ColTypeNumeric.cpp
@@ -43,6 +43,12 @@ ColumnTypeNumeric::ColumnTypeNumeric ()
   _type = "numeric";
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnTypeNumeric::validate (const std::string& input) const
+{
+  return input.length () ? true : false;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 void ColumnTypeNumeric::modify (Task& task, const std::string& value)
 {
diff --git a/src/columns/ColTypeNumeric.h b/src/columns/ColTypeNumeric.h
index ff2f9c12b..9cc68a62f 100644
--- a/src/columns/ColTypeNumeric.h
+++ b/src/columns/ColTypeNumeric.h
@@ -35,6 +35,7 @@ class ColumnTypeNumeric : public Column
 {
 public:
   ColumnTypeNumeric ();
+  virtual bool validate (const std::string&) const;
   virtual void modify (Task&, const std::string&);
 };
 
diff --git a/src/columns/ColTypeString.cpp b/src/columns/ColTypeString.cpp
index af91ae008..5b3856a0a 100644
--- a/src/columns/ColTypeString.cpp
+++ b/src/columns/ColTypeString.cpp
@@ -43,6 +43,12 @@ ColumnTypeString::ColumnTypeString ()
   _type = "string";
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnTypeString::validate (const std::string& input) const
+{
+  return input.length () ? true : false;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 void ColumnTypeString::modify (Task& task, const std::string& value)
 {
diff --git a/src/columns/ColTypeString.h b/src/columns/ColTypeString.h
index 697c98e51..21d3b32f9 100644
--- a/src/columns/ColTypeString.h
+++ b/src/columns/ColTypeString.h
@@ -35,6 +35,7 @@ class ColumnTypeString : public Column
 {
 public:
   ColumnTypeString ();
+  virtual bool validate (const std::string&) const;
   virtual void modify (Task&, const std::string&);
 };
 
diff --git a/src/columns/Column.cpp b/src/columns/Column.cpp
index 432f6def8..81a03f1e5 100644
--- a/src/columns/Column.cpp
+++ b/src/columns/Column.cpp
@@ -292,12 +292,6 @@ void Column::setStyle (const std::string& style)
   _style = style;
 }
 
-////////////////////////////////////////////////////////////////////////////////
-bool Column::validate (const std::string& input) const
-{
-  return input.length () ? true : false;
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 // All integer values are right-justified.
 void Column::renderInteger (
diff --git a/src/columns/Column.h b/src/columns/Column.h
index d064a261e..32f117933 100644
--- a/src/columns/Column.h
+++ b/src/columns/Column.h
@@ -57,12 +57,12 @@ public:
   virtual void setLabel  (const std::string& value) { _label = value;  }
   virtual void setReport (const std::string& value) { _report = value; }
 
-  virtual bool validate (const std::string&) const;
   virtual void measure (const std::string&, unsigned int&, unsigned int&)           {};
   virtual void measure (Task&, unsigned int&, unsigned int&)                        {};
   virtual void renderHeader (std::vector <std::string>&, int, Color&);
   virtual void render (std::vector <std::string>&, const std::string&, int, Color&) {};
   virtual void render (std::vector <std::string>&, Task&, int, Color&)              {};
+  virtual bool validate (const std::string&) const                                  {return false;};
   virtual void modify (Task&, const std::string&)                                   {};
 
 protected: