diff --git a/src/commands/CMakeLists.txt b/src/commands/CMakeLists.txt
index 38ab0e30..ed2a381a 100644
--- a/src/commands/CMakeLists.txt
+++ b/src/commands/CMakeLists.txt
@@ -30,7 +30,6 @@ set (commands_SRCS CmdCancel.cpp
                    CmdTag.cpp
                    CmdTags.cpp
                    CmdTrack.cpp
-                   CmdUndo.cpp
                    CmdUntag.cpp)
 
 add_library (commands STATIC ${commands_SRCS})
diff --git a/src/commands/CmdHelp.cpp b/src/commands/CmdHelp.cpp
index 305c15fa..0fa930e2 100644
--- a/src/commands/CmdHelp.cpp
+++ b/src/commands/CmdHelp.cpp
@@ -89,8 +89,6 @@ int CmdHelpUsage ()
             << "       rc.<name>=<value>\n"
             << '\n';
 
-  // TODO undo
-
   // TODO List all extensions.
 
   return 0;
@@ -822,8 +820,6 @@ int CmdHelp (const CLI& cli)
                 << "same as the 'start' command.\n"
                 << '\n';
 
-    // TODO undo
-
     // Ruler                 1         2         3         4         5         6         7         8
     //              12345678901234567890123456789012345678901234567890123456789012345678901234567890
     else if (words[0] == "untag")
diff --git a/src/commands/CmdUndo.cpp b/src/commands/CmdUndo.cpp
deleted file mode 100644
index 12a080fd..00000000
--- a/src/commands/CmdUndo.cpp
+++ /dev/null
@@ -1,41 +0,0 @@
-////////////////////////////////////////////////////////////////////////////////
-//
-// Copyright 2015 - 2016, Paul Beckingham, Federico Hernandez.
-//
-// Permission is hereby granted, free of charge, to any person obtaining a copy
-// of this software and associated documentation files (the "Software"), to deal
-// in the Software without restriction, including without limitation the rights
-// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-// copies of the Software, and to permit persons to whom the Software is
-// furnished to do so, subject to the following conditions:
-//
-// The above copyright notice and this permission notice shall be included
-// in all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
-// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
-// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-// SOFTWARE.
-//
-// http://www.opensource.org/licenses/mit-license.php
-//
-////////////////////////////////////////////////////////////////////////////////
-
-#include <cmake.h>
-#include <iostream>
-
-////////////////////////////////////////////////////////////////////////////////
-int CmdUndo ()
-{
-  std::cout << "[undo: revert last change]\n";
-
-  // TODO Extract most recent transaction.
-  // TODO Apply inverse.
-
-  return 0;
-}
-
-////////////////////////////////////////////////////////////////////////////////
diff --git a/src/commands/commands.h b/src/commands/commands.h
index 25afb7fb..7d8c4bb5 100644
--- a/src/commands/commands.h
+++ b/src/commands/commands.h
@@ -56,7 +56,6 @@ int CmdStop          (const CLI&, Rules&, Database&                   );
 int CmdTag           (const CLI&, Rules&, Database&                   );
 int CmdTags          (            Rules&, Database&                   );
 int CmdTrack         (const CLI&, Rules&, Database&                   );
-int CmdUndo          (                                                );
 int CmdUntag         (const CLI&, Rules&, Database&                   );
 
 int CmdChartDay      (const CLI&, Rules&, Database&                   );
diff --git a/src/init.cpp b/src/init.cpp
index b35dad65..2bb02ea7 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -79,7 +79,6 @@ void initializeEntities (CLI& cli)
   cli.entity ("command", "tag");
   cli.entity ("command", "tags");
   cli.entity ("command", "track");
-  cli.entity ("command", "undo");
   cli.entity ("command", "untag");
 
   // Some command list themselves as extensions, to integrate with the real
@@ -280,7 +279,6 @@ int dispatchCommand (
     else if (command == "tag")         status = CmdTag           (cli, rules, database            );
     else if (command == "tags")        status = CmdTags          (     rules, database            );
     else if (command == "track")       status = CmdTrack         (cli, rules, database            );
-    else if (command == "undo")        status = CmdUndo          (                                );
     else if (command == "untag")       status = CmdUntag         (cli, rules, database            );
     else if (command == "week")        status = CmdChartWeek     (cli, rules, database            );
     else                               status = CmdReport        (cli, rules, database, extensions);