diff --git a/src/function_group.hh b/src/function_group.hh
deleted file mode 100644
index 025a8f92..00000000
--- a/src/function_group.hh
+++ /dev/null
@@ -1,76 +0,0 @@
-#ifndef function_group_hh_INCLUDED
-#define function_group_hh_INCLUDED
-
-#include "exception.hh"
-#include "id_map.hh"
-#include "string.hh"
-
-namespace Kakoune
-{
-
-struct group_not_found : public runtime_error
-{
-    using runtime_error::runtime_error;
-};
-
-template<typename... Args>
-class FunctionGroup
-{
-public:
-    using Function = std::function<void (Args...)>;
-    using FunctionAndId = std::pair<String, std::function<void (Args...)>>;
-
-    void operator()(Args... args)
-    {
-        for (auto& func : m_functions)
-           func.second(std::forward<Args>(args)...);
-    }
-
-    void append(FunctionAndId&& function)
-    {
-        if (m_functions.contains(function.first))
-            throw runtime_error("duplicate id: " + function.first);
-
-        m_functions.append(std::forward<FunctionAndId>(function));
-    }
-    void remove(StringView id)
-    {
-        m_functions.remove(id);
-    }
-
-    FunctionGroup& get_group(StringView path, Codepoint path_separator = 0)
-    {
-        auto sep_it = std::find(path.begin(), path.end(), path_separator);
-        StringView id(path.begin(), sep_it);
-        auto it = m_functions.find(id);
-        if (it == m_functions.end())
-            throw group_not_found("no such id: "_str + id);
-        FunctionGroup* group = it->second.template target<FunctionGroup>();
-        if (not group)
-            throw group_not_found("not a group: "_str + id);
-        if (sep_it != path.end())
-            return group->get_group(StringView(sep_it+1, path.end()), path_separator);
-        else
-            return  *group;
-    }
-
-    CandidateList complete_id(StringView prefix, ByteCount cursor_pos) const
-    {
-        return m_functions.complete_id(prefix, cursor_pos);
-    }
-
-    CandidateList complete_group_id(StringView prefix, ByteCount cursor_pos) const
-    {
-        return m_functions.complete_id_if(
-            prefix, cursor_pos, [](const FunctionAndId& func) {
-                return func.second.template target<FunctionGroup>() != nullptr;
-            });
-    }
-
-private:
-    id_map<Function> m_functions;
-};
-
-}
-
-#endif // function_group_hh_INCLUDED
diff --git a/src/function_registry.hh b/src/function_registry.hh
index 1565c36a..b7296eac 100644
--- a/src/function_registry.hh
+++ b/src/function_registry.hh
@@ -4,6 +4,7 @@
 #include "completion.hh"
 #include "id_map.hh"
 #include "string.hh"
+#include "exception.hh"
 
 namespace Kakoune
 {
diff --git a/src/highlighter.hh b/src/highlighter.hh
index 2c7bb720..8060675d 100644
--- a/src/highlighter.hh
+++ b/src/highlighter.hh
@@ -1,7 +1,6 @@
 #ifndef highlighter_hh_INCLUDED
 #define highlighter_hh_INCLUDED
 
-#include "function_group.hh"
 #include "function_registry.hh"
 #include "memoryview.hh"
 #include "string.hh"
@@ -30,17 +29,11 @@ using HighlighterFunc = std::function<void (const Context& context, HighlightFla
 using HighlighterAndId = std::pair<String, HighlighterFunc>;
 using HighlighterParameters = memoryview<String>;
 using HighlighterFactory = std::function<HighlighterAndId (HighlighterParameters params)>;
-using HighlighterGroup = FunctionGroup<const Context&, HighlightFlags, DisplayBuffer&>;
 
 struct HighlighterRegistry : FunctionRegistry<HighlighterFactory>,
                              Singleton<HighlighterRegistry>
 {};
 
-struct DefinedHighlighters : public HighlighterGroup,
-                             public Singleton<DefinedHighlighters>
-{
-};
-
 }
 
 #endif // highlighter_hh_INCLUDED
diff --git a/src/highlighter_group.cc b/src/highlighter_group.cc
new file mode 100644
index 00000000..c86e51cc
--- /dev/null
+++ b/src/highlighter_group.cc
@@ -0,0 +1,53 @@
+#include "highlighter_group.hh"
+
+namespace Kakoune
+{
+
+void HighlighterGroup::operator()(const Context& context, HighlightFlags flags, DisplayBuffer& display_buffer)
+{
+    for (auto& hl : m_highlighters)
+       hl.second(context, flags, display_buffer);
+}
+
+void HighlighterGroup::append(HighlighterAndId&& hl)
+{
+    if (m_highlighters.contains(hl.first))
+        throw runtime_error("duplicate id: " + hl.first);
+
+    m_highlighters.append(std::move(hl));
+}
+void HighlighterGroup::remove(StringView id)
+{
+    m_highlighters.remove(id);
+}
+
+HighlighterGroup& HighlighterGroup::get_group(StringView path, Codepoint path_separator)
+{
+    auto sep_it = std::find(path.begin(), path.end(), path_separator);
+    StringView id(path.begin(), sep_it);
+    auto it = m_highlighters.find(id);
+    if (it == m_highlighters.end())
+        throw group_not_found("no such id: "_str + id);
+    HighlighterGroup* group = it->second.template target<HighlighterGroup>();
+    if (not group)
+        throw group_not_found("not a group: "_str + id);
+    if (sep_it != path.end())
+        return group->get_group(StringView(sep_it+1, path.end()), path_separator);
+    else
+        return *group;
+}
+
+CandidateList HighlighterGroup::complete_id(StringView prefix, ByteCount cursor_pos) const
+{
+    return m_highlighters.complete_id(prefix, cursor_pos);
+}
+
+CandidateList HighlighterGroup::complete_group_id(StringView prefix, ByteCount cursor_pos) const
+{
+    return m_highlighters.complete_id_if(
+        prefix, cursor_pos, [](const HighlighterAndId& func) {
+            return func.second.template target<HighlighterGroup>() != nullptr;
+        });
+}
+
+}
diff --git a/src/highlighter_group.hh b/src/highlighter_group.hh
new file mode 100644
index 00000000..8445e445
--- /dev/null
+++ b/src/highlighter_group.hh
@@ -0,0 +1,41 @@
+#ifndef highlighter_group_hh_INCLUDED
+#define highlighter_group_hh_INCLUDED
+
+#include "exception.hh"
+#include "id_map.hh"
+#include "highlighter.hh"
+#include "utils.hh"
+
+namespace Kakoune
+{
+
+struct group_not_found : public runtime_error
+{
+    using runtime_error::runtime_error;
+};
+
+class HighlighterGroup
+{
+public:
+    void operator()(const Context& context, HighlightFlags flags, DisplayBuffer& display_buffer);
+
+    void append(HighlighterAndId&& hl);
+    void remove(StringView id);
+
+    HighlighterGroup& get_group(StringView path, Codepoint path_separator = 0);
+
+    CandidateList complete_id(StringView prefix, ByteCount cursor_pos) const;
+    CandidateList complete_group_id(StringView prefix, ByteCount cursor_pos) const;
+
+private:
+    id_map<HighlighterFunc> m_highlighters;
+};
+
+struct DefinedHighlighters : public HighlighterGroup,
+                             public Singleton<DefinedHighlighters>
+{
+};
+
+}
+
+#endif // highlighter_group_hh_INCLUDED
diff --git a/src/highlighters.cc b/src/highlighters.cc
index ab765bb2..9cb66a05 100644
--- a/src/highlighters.cc
+++ b/src/highlighters.cc
@@ -1,5 +1,6 @@
 #include "highlighters.hh"
 
+#include "highlighter_group.hh"
 #include "assert.hh"
 #include "buffer_utils.hh"
 #include "color_registry.hh"
diff --git a/src/window.hh b/src/window.hh
index 6115f42d..74d4fa37 100644
--- a/src/window.hh
+++ b/src/window.hh
@@ -3,7 +3,7 @@
 
 #include "completion.hh"
 #include "display_buffer.hh"
-#include "highlighter.hh"
+#include "highlighter_group.hh"
 #include "selection.hh"
 #include "hook_manager.hh"
 #include "option_manager.hh"