diff --git a/src/Task.cpp b/src/Task.cpp
index b5d22ed63..10ae25f0c 100644
--- a/src/Task.cpp
+++ b/src/Task.cpp
@@ -51,6 +51,8 @@
 #ifdef PRODUCT_TASKWARRIOR
 #include <main.h>
 
+#include <E9.h>
+
 #define APPROACHING_INFINITY 1000   // Close enough.  This isn't rocket surgery.
 
 extern Context context;
@@ -1734,3 +1736,228 @@ float Task::urgency_blocking () const
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+void Task::modify (
+  const A3& arguments,
+  std::string& description)
+{
+  // Coalesce arguments together into sets to be processed as a batch.
+  unsigned int pos = 0;
+  Arg arg;
+  while ((*this).next_mod_group (arguments, arg, pos))
+  {
+    // Attributes are essentially name:value pairs, and correspond directly
+    // to stored attributes.
+    if (arg._category == Arg::cat_attr)
+    {
+      std::string name;
+      std::string value;
+      A3::extract_attr (arg._raw, name, value);
+      if (A3::is_attribute (name, name))  // Canonicalize
+      {
+        //std::cout << "# Task::modify_task name='" << name << "' value='" << value << "'\n";
+
+        // Get the column info.
+        Column* column = context.columns[name];
+
+        if (value == "")
+        {
+          (*this).remove (name);
+        }
+        else
+        {
+          // Dependencies are used as IDs.
+          if (name == "depends")
+          {
+            // Parse IDs
+            std::vector <std::string> deps;
+            split (deps, value, ',');
+
+            // Apply or remove dendencies in turn.
+            std::vector <std::string>::iterator i;
+            for (i = deps.begin (); i != deps.end (); i++)
+            {
+              bool removal = false;
+              std::string& dep = *i;
+
+              if (dep[0] == '-')
+              {
+                removal = true;
+                dep = i->substr(1, std::string::npos);
+              }
+
+              std::vector <int> ids;
+              // Crude UUID check
+              if (dep.length () == 36)
+              {
+                int id = context.tdb2.pending.id (dep);
+                ids.push_back (id);
+              }
+              else
+                A3::extract_id (dep, ids);
+
+              std::vector <int>::iterator id;
+              for (id = ids.begin (); id != ids.end(); id++)
+                if (removal)
+                  (*this).removeDependency (*id);
+                else
+                  (*this).addDependency (*id);
+            }
+          }
+
+          // Priorities are converted to upper case.
+          else if (name == "priority")
+          {
+            (*this).set (name, upperCase (value));
+          }
+
+          // Dates are special, maybe.
+          else if (column->type () == "date")
+          {
+            // All values must be eval'd first.
+            A3 value_tokens;
+            value_tokens.capture (value);
+            value_tokens = value_tokens.postfix (value_tokens.tokenize (value_tokens));
+
+            E9 e (value_tokens);
+            std::string result = e.evalExpression ((*this));
+            context.debug (std::string ("Eval '") + value + "' --> '" + result + "'");
+
+            // If the date value is less than 5 years, it is a duration, not a
+            // date, therefore add 'now'.
+            long l = (long) strtod (result.c_str (), NULL);
+            if (labs (l) < 5 * 365 * 86400)
+            {
+              Duration dur (value);
+              Date now;
+              now += l;
+              (*this).set (name, now.toEpochString ());
+            }
+            else
+            {
+              Date d (result, context.config.get ("dateformat"));
+              (*this).set (name, d.toEpochString ());
+            }
+          }
+
+          // Durations too.
+          else if (name == "recur" ||
+                   column->type () == "duration")
+          {
+            // All values must be eval'd first, in this case, just to catch errors.
+            A3 value_tokens;
+            value_tokens.capture (value);
+            value_tokens = value_tokens.postfix (value_tokens.tokenize (value_tokens));
+
+            E9 e (value_tokens);
+            std::string result = e.evalExpression ((*this));
+            context.debug (std::string ("Eval '") + value + "' --> '" + result + "'");
+
+            Duration d (value);
+
+            // Deliberately storing the 'raw' value, which is necessary for
+            // durations like 'weekday'..
+            (*this).set (name, name == "recur" ? value : result);
+          }
+
+          // Need handling for numeric types, used by UDAs.
+          else if (column->type () == "numeric")
+          {
+            A3 value_tokens;
+            value_tokens.capture (value);
+            value_tokens = value_tokens.postfix (value_tokens.tokenize (value_tokens));
+
+            E9 e (value_tokens);
+            std::string result = e.evalExpression ((*this));
+            context.debug (std::string ("Eval '") + value + "' --> '" + result + "'");
+
+            Nibbler n (result);
+            double d;
+            if (n.getNumber (d) &&
+                n.depleted ())
+              (*this).set (name, result);
+            else
+              throw format (STRING_UDA_NUMERIC, result);
+          }
+
+          // By default, just add/remove it.
+          else
+          {
+            if (column->validate (value))
+              (*this).set (name, value);
+            else
+              throw format (STRING_INVALID_MOD, name, value);
+          }
+
+          // Warn about deprecated/obsolete attribute usage.
+          legacyAttributeCheck (name);
+        }
+      }
+      else
+        throw format (STRING_CMD_ADD_BAD_ATTRIBUTE, name);
+    }
+
+    // Tags need special handling because they are essentially a vector stored
+    // in a single string, therefore Task::{add,remove}Tag must be called as
+    // appropriate.
+    else if (arg._category == Arg::cat_tag)
+    {
+      char type;
+      std::string value;
+      A3::extract_tag (arg._raw, type, value);
+
+      if (type == '+')
+      {
+        (*this).addTag (value);
+        feedback_special_tags ((*this), value);
+      }
+      else
+        (*this).removeTag (value);
+    }
+
+    // Substitutions.
+    else if (arg._category == Arg::cat_subst)
+    {
+      std::string from;
+      std::string to;
+      bool global;
+      A3::extract_subst (arg._raw, from, to, global);
+      (*this).substitute (from, to, global);
+    }
+
+    // Anything else is essentially downgraded to 'word' and considered part of
+    // the description.
+    else
+    {
+      if (description.length ())
+        description += " ";
+
+      description += arg._raw;
+    }
+  }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Special processing for modifications.
+bool Task::next_mod_group (const A3& input, Arg& arg, unsigned int& pos)
+{
+  if (pos < input.size ())
+  {
+    arg = input[pos++];
+
+    if (arg._raw == "depends")
+    {
+      while (pos < input.size () &&
+             (input[pos]._category == Arg::cat_op ||
+              input[pos]._type == Arg::type_number))
+      {
+        arg._raw += input[pos++]._raw;
+      }
+    }
+
+    return true;
+  }
+
+  return false;
+}
+
+////////////////////////////////////////////////////////////////////////////////
\ No newline at end of file
diff --git a/src/Task.h b/src/Task.h
index 826adb671..5fcb8525b 100644
--- a/src/Task.h
+++ b/src/Task.h
@@ -32,6 +32,7 @@
 #include <map>
 #include <string>
 #include <stdio.h>
+#include <A3.h>
 
 class Task : public std::map <std::string, std::string>
 {
@@ -143,6 +144,9 @@ public:
   float urgency_c () const;
   float urgency ();
 
+  void modify (const A3&, std::string&);
+  bool next_mod_group (const A3&, Arg&, unsigned int&);
+
 private:
   int determineVersion (const std::string&);
   void parseJSON (const std::string&);
diff --git a/src/commands/Command.cpp b/src/commands/Command.cpp
index 574040a6e..0cc07d0e0 100644
--- a/src/commands/Command.cpp
+++ b/src/commands/Command.cpp
@@ -460,200 +460,8 @@ void Command::modify_task (
   const A3& arguments,
   std::string& description)
 {
-  // Coalesce arguments together into sets to be processed as a batch.
-  unsigned int pos = 0;
-  Arg arg;
-  while (next_mod_group (arguments, arg, pos))
-  {
-    // Attributes are essentially name:value pairs, and correspond directly
-    // to stored attributes.
-    if (arg._category == Arg::cat_attr)
-    {
-      std::string name;
-      std::string value;
-      A3::extract_attr (arg._raw, name, value);
-      if (A3::is_attribute (name, name))  // Canonicalize
-      {
-        //std::cout << "# Command::modify_task name='" << name << "' value='" << value << "'\n";
-
-        // Get the column info.
-        Column* column = context.columns[name];
-
-        if (value == "")
-        {
-          task.remove (name);
-        }
-        else
-        {
-          // Dependencies are used as IDs.
-          if (name == "depends")
-          {
-            // Parse IDs
-            std::vector <std::string> deps;
-            split (deps, value, ',');
-
-            // Apply or remove dendencies in turn.
-            std::vector <std::string>::iterator i;
-            for (i = deps.begin (); i != deps.end (); i++)
-            {
-              bool removal = false;
-              std::string& dep = *i;
-
-              if (dep[0] == '-')
-              {
-                removal = true;
-                dep = i->substr(1, std::string::npos);
-              }
-
-              std::vector <int> ids;
-              // Crude UUID check
-              if (dep.length () == 36)
-              {
-                int id = context.tdb2.pending.id (dep);
-                ids.push_back (id);
-              }
-              else
-                A3::extract_id (dep, ids);
-
-              std::vector <int>::iterator id;
-              for (id = ids.begin (); id != ids.end(); id++)
-                if (removal)
-                  task.removeDependency (*id);
-                else
-                  task.addDependency (*id);
-            }
-          }
-
-          // Priorities are converted to upper case.
-          else if (name == "priority")
-          {
-            task.set (name, upperCase (value));
-          }
-
-          // Dates are special, maybe.
-          else if (column->type () == "date")
-          {
-            // All values must be eval'd first.
-            A3 value_tokens;
-            value_tokens.capture (value);
-            value_tokens = value_tokens.postfix (value_tokens.tokenize (value_tokens));
-
-            E9 e (value_tokens);
-            std::string result = e.evalExpression (task);
-            context.debug (std::string ("Eval '") + value + "' --> '" + result + "'");
-
-            // If the date value is less than 5 years, it is a duration, not a
-            // date, therefore add 'now'.
-            long l = (long) strtod (result.c_str (), NULL);
-            if (labs (l) < 5 * 365 * 86400)
-            {
-              Duration dur (value);
-              Date now;
-              now += l;
-              task.set (name, now.toEpochString ());
-            }
-            else
-            {
-              Date d (result, context.config.get ("dateformat"));
-              task.set (name, d.toEpochString ());
-            }
-          }
-
-          // Durations too.
-          else if (name == "recur" ||
-                   column->type () == "duration")
-          {
-            // All values must be eval'd first, in this case, just to catch errors.
-            A3 value_tokens;
-            value_tokens.capture (value);
-            value_tokens = value_tokens.postfix (value_tokens.tokenize (value_tokens));
-
-            E9 e (value_tokens);
-            std::string result = e.evalExpression (task);
-            context.debug (std::string ("Eval '") + value + "' --> '" + result + "'");
-
-            Duration d (value);
-
-            // Deliberately storing the 'raw' value, which is necessary for
-            // durations like 'weekday'..
-            task.set (name, name == "recur" ? value : result);
-          }
-
-          // Need handling for numeric types, used by UDAs.
-          else if (column->type () == "numeric")
-          {
-            A3 value_tokens;
-            value_tokens.capture (value);
-            value_tokens = value_tokens.postfix (value_tokens.tokenize (value_tokens));
-
-            E9 e (value_tokens);
-            std::string result = e.evalExpression (task);
-            context.debug (std::string ("Eval '") + value + "' --> '" + result + "'");
-
-            Nibbler n (result);
-            double d;
-            if (n.getNumber (d) &&
-                n.depleted ())
-              task.set (name, result);
-            else
-              throw format (STRING_UDA_NUMERIC, result);
-          }
-
-          // By default, just add/remove it.
-          else
-          {
-            if (column->validate (value))
-              task.set (name, value);
-            else
-              throw format (STRING_INVALID_MOD, name, value);
-          }
-
-          // Warn about deprecated/obsolete attribute usage.
-          legacyAttributeCheck (name);
-        }
-      }
-      else
-        throw format (STRING_CMD_ADD_BAD_ATTRIBUTE, name);
-    }
-
-    // Tags need special handling because they are essentially a vector stored
-    // in a single string, therefore Task::{add,remove}Tag must be called as
-    // appropriate.
-    else if (arg._category == Arg::cat_tag)
-    {
-      char type;
-      std::string value;
-      A3::extract_tag (arg._raw, type, value);
-
-      if (type == '+')
-      {
-        task.addTag (value);
-        feedback_special_tags (task, value);
-      }
-      else
-        task.removeTag (value);
-    }
-
-    // Substitutions.
-    else if (arg._category == Arg::cat_subst)
-    {
-      std::string from;
-      std::string to;
-      bool global;
-      A3::extract_subst (arg._raw, from, to, global);
-      task.substitute (from, to, global);
-    }
-
-    // Anything else is essentially downgraded to 'word' and considered part of
-    // the description.
-    else
-    {
-      if (description.length ())
-        description += " ";
-
-      description += arg._raw;
-    }
-  }
+  // Utilize Task::modify
+  task.modify(arguments, description);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -737,27 +545,3 @@ bool Command::permission (
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-// Special processing for modifications.
-bool Command::next_mod_group (const A3& input, Arg& arg, unsigned int& pos)
-{
-  if (pos < input.size ())
-  {
-    arg = input[pos++];
-
-    if (arg._raw == "depends")
-    {
-      while (pos < input.size () &&
-             (input[pos]._category == Arg::cat_op ||
-              input[pos]._type == Arg::type_number))
-      {
-        arg._raw += input[pos++]._raw;
-      }
-    }
-
-    return true;
-  }
-
-  return false;
-}
-
-////////////////////////////////////////////////////////////////////////////////
diff --git a/src/commands/Command.h b/src/commands/Command.h
index 1c822d2fe..2e3453d48 100644
--- a/src/commands/Command.h
+++ b/src/commands/Command.h
@@ -66,8 +66,6 @@ protected:
   void safety ();
   bool permission (const Task&, const std::string&, unsigned int);
 
-  bool next_mod_group (const A3&, Arg&, unsigned int&);
-
 protected:
   std::string _keyword;
   std::string _usage;