diff --git a/.travis.yml b/.travis.yml
index fb8f529d..03e3e1ed 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -21,7 +21,7 @@ before_install:
 install:
   - if [ $TRAVIS_OS_NAME = linux ]; then
       if [ "$CXX" = "g++" ]; then
-        export CXX=g++-6;
+        export CXX=g++-5;
       fi;
     elif [ $TRAVIS_OS_NAME = osx ]; then
       brew outdated gcc || brew upgrade gcc;
@@ -35,8 +35,8 @@ addons:
     sources:
       - ubuntu-toolchain-r-test
     packages:
-      - libstdc++-6-dev
-      - g++-6
+      - libstdc++-5-dev
+      - g++-5
       - libncursesw5-dev
   coverity_scan:
     project:
diff --git a/src/commands.cc b/src/commands.cc
index 02e797c5..dcee0281 100644
--- a/src/commands.cc
+++ b/src/commands.cc
@@ -1498,33 +1498,32 @@ const CommandDesc declare_option_cmd = {
 };
 
 template<bool unmap>
-static auto map_key_completer =
-    [](const Context& context, CompletionFlags flags,
-       CommandParameters params, size_t token_to_complete,
-       ByteCount pos_in_token) -> Completions
+static Completions map_key_completer(const Context& context, CompletionFlags flags,
+                                     CommandParameters params, size_t token_to_complete,
+                                     ByteCount pos_in_token)
+{
+    if (token_to_complete == 0)
+        return { 0_byte, params[0].length(),
+                 complete(params[0], pos_in_token, scopes) };
+    if (token_to_complete == 1)
     {
-        if (token_to_complete == 0)
-            return { 0_byte, params[0].length(),
-                     complete(params[0], pos_in_token, scopes) };
-        if (token_to_complete == 1)
-        {
-            auto& user_modes = get_scope(params[0], context).keymaps().user_modes();
-            return { 0_byte, params[1].length(),
-                     complete(params[1], pos_in_token, concatenated(modes, user_modes) | gather<Vector<String>>()) };
-        }
-        if (unmap and token_to_complete == 2)
-        {
-            KeymapManager& keymaps = get_scope(params[0], context).keymaps();
-            KeymapMode keymap_mode = parse_keymap_mode(params[1], keymaps.user_modes());
-            KeyList keys = keymaps.get_mapped_keys(keymap_mode);
+        auto& user_modes = get_scope(params[0], context).keymaps().user_modes();
+        return { 0_byte, params[1].length(),
+                 complete(params[1], pos_in_token, concatenated(modes, user_modes) | gather<Vector<String>>()) };
+    }
+    if (unmap and token_to_complete == 2)
+    {
+        KeymapManager& keymaps = get_scope(params[0], context).keymaps();
+        KeymapMode keymap_mode = parse_keymap_mode(params[1], keymaps.user_modes());
+        KeyList keys = keymaps.get_mapped_keys(keymap_mode);
 
-            return { 0_byte, params[2].length(),
-                     complete(params[2], pos_in_token,
-                              keys | transform([](Key k) { return key_to_str(k); })
-                                   | gather<Vector<String>>()) };
-        }
-        return {};
-    };
+        return { 0_byte, params[2].length(),
+                 complete(params[2], pos_in_token,
+                          keys | transform([](Key k) { return key_to_str(k); })
+                               | gather<Vector<String>>()) };
+    }
+    return {};
+}
 
 const CommandDesc map_key_cmd = {
     "map",