diff --git a/src/commands/CmdExtensions.cpp b/src/commands/CmdExtensions.cpp
index 559e74f3..eb6bad33 100644
--- a/src/commands/CmdExtensions.cpp
+++ b/src/commands/CmdExtensions.cpp
@@ -33,7 +33,9 @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // Enumerate all extensions.
-int CmdExtensions (Rules& rules, Extensions& extensions)
+int CmdExtensions (
+  Rules& rules,
+  const Extensions& extensions)
 {
   Table t;
   t.width (1024);
diff --git a/src/commands/commands.h b/src/commands/commands.h
index 06b74954..16707b47 100644
--- a/src/commands/commands.h
+++ b/src/commands/commands.h
@@ -36,7 +36,6 @@ int CmdClear       (                                    );
 int CmdConfig      (                                    );
 int CmdContinue    (      Rules&, Database&             );
 int CmdDefault     (      Rules&, Database&             );
-int CmdExtensions  (      Rules&,            Extensions&);
 int CmdGaps        (                                    );
 int CmdHelpUsage   (                                    );
 int CmdHelp        (CLI&                                );
@@ -48,5 +47,6 @@ int CmdTrack       (CLI&, Rules&, Database&             );
 int CmdUndo        (                                    );
 int CmdDiagnostics (            Rules&, Database&, const Extensions&);
 int CmdExport      (const CLI&, Rules&, Database&                   );
+int CmdExtensions  (            Rules&,            const Extensions&);
 
 #endif