diff --git a/include/memon.hpp b/include/memon.hpp
index b1f7775..f9c857e 100644
--- a/include/memon.hpp
+++ b/include/memon.hpp
@@ -1,4 +1,5 @@
-#pragma once
+#ifndef MEMON_HPP_
+#define MEMON_HPP_
 
 #include <cassert>
 #include <set>
@@ -168,6 +169,7 @@ namespace stepland {
             } else {
                 m.load_from_memon_fallback(j);
             }
+            return file;
         }
 
         /*
@@ -176,9 +178,9 @@ namespace stepland {
         *     this way the difficulty names are guaranteed to be unique
         * 	- "jacket path" is now "album cover path" because engrish much ?
         */
-        void load_from_memon_v0_1_0(nlohmann::json memon) {
+        void load_from_memon_v0_1_0(nlohmann::json memon_json) {
             
-            auto metadata = memon.at("metadata");
+            auto metadata = memon_json.at("metadata");
             if (not metadata.is_object()) {
                 throw std::invalid_argument("metadata fields is not an object");
             }
@@ -190,11 +192,11 @@ namespace stepland {
             this->BPM = metadata.value("BPM",120.0f);
             this->offset = metadata.value("offset",0.0f);
 
-            if (not memon.at("data").is_object()) {
+            if (not memon_json.at("data").is_object()) {
                 throw std::invalid_argument("data field is not an object");
             }
 
-            for (auto& [dif_name, chart_json] : memon.at("data").items()) {
+            for (auto& [dif_name, chart_json] : memon_json.at("data").items()) {
                 
                 chart new_chart;
                 new_chart.level = chart_json.value("level", 0);
@@ -234,9 +236,9 @@ namespace stepland {
         *   - "data" is an array of charts, each with a difficulty name
         *   - the album cover path field is named "jacket path"
         */
-        void load_from_memon_fallback(nlohmann::json memon) {
+        void load_from_memon_fallback(nlohmann::json memon_json) {
             
-            auto metadata = memon.at("metadata");
+            auto metadata = memon_json.at("metadata");
             if (not metadata.is_object()) {
                 throw std::invalid_argument("metadata fields is not an object");
             }
@@ -248,11 +250,11 @@ namespace stepland {
             this->BPM = metadata.value("BPM",120.f);
             this->offset = metadata.value("offset",0.f);
 
-            if (not memon.at("data").is_array()) {
+            if (not memon_json.at("data").is_array()) {
                 throw std::invalid_argument("data field is not an array");
             }
 
-            for (auto& chart_json : memon.at("data")) {
+            for (auto& chart_json : memon_json.at("data")) {
                 chart new_chart;
                 new_chart.level = chart_json.value("level", 0);
                 new_chart.resolution = chart_json.at("resolution").get<int>();
@@ -289,4 +291,6 @@ namespace stepland {
             }
         }
     };
-}
\ No newline at end of file
+}
+
+#endif /* MEMON_HPP_ */
diff --git a/meson.build b/meson.build
index 061dcc4..9628ea5 100644
--- a/meson.build
+++ b/meson.build
@@ -41,5 +41,12 @@ executable(
     'jujube',
     sources,
     dependencies: [sfml, filesystem],
-    include_directories : include_directories('include')
+    include_directories : include_directories('include'),
+    cpp_args : [
+        '-Wall',
+        '-Wextra',
+        '-Wshadow',
+        '-Wnon-virtual-dtor',
+        '-pedantic'
+    ]
 )
\ No newline at end of file
diff --git a/src/Data/Note.cpp b/src/Data/Note.cpp
index 732cf0c..fdfd86d 100644
--- a/src/Data/Note.cpp
+++ b/src/Data/Note.cpp
@@ -1,73 +1,83 @@
 #include "Note.hpp"
 
+namespace Data {
+    
+    Note::Note(
+        unsigned int t_position,
+        sf::Time t_timing,
+        sf::Time t_length,
+        unsigned int t_tail_position
+    ) : 
+        position(t_position),
+        timing(t_timing),
+        length(t_length),
+        tail_position(t_tail_position)
+    {
+        if (t_position > 15) {  
+            throw std::out_of_range(
+                "Tried creating a note with invalid position : "
+                +std::to_string(t_position)
+            );
+        }
 
-Data::Note::Note(
-    unsigned int t_position,
-    sf::Time t_timing,
-    sf::Time t_length,
-    unsigned int t_tail_position
-) : 
-    position(t_position),
-    timing(t_timing),
-    length(t_length),
-    tail_position(t_tail_position)
-{
-    if (t_position > 15) {  
-        throw std::out_of_range("Tried creating a note with invalid position : "+std::to_string(t_position));
-    }
-
-    if (t_length.asMicroseconds() < 0) {
-        throw std::out_of_range("Tried creating a long note with negative length : "+std::to_string(t_length.asSeconds)+ "s");
-
-    }
-    if (t_length.asMicroseconds() > 0) {
-        if (t_tail_position > 5) {
-            throw std::out_of_range("Tried creating a long note with invalid tail position : "+std::to_string(t_tail_position));
+        if (t_length.asMicroseconds() < 0) {
+            throw std::out_of_range(
+                "Tried creating a long note with negative length : "
+                +std::to_string(t_length.asSeconds())+"s"
+            );
+        }
+        if (t_length.asMicroseconds() > 0) {
+            if (t_tail_position > 5) {
+                throw std::out_of_range(
+                    "Tried creating a long note with invalid tail position : "
+                    +std::to_string(t_tail_position)
+                );
+            }
         }
     }
-}
 
-bool Data::Note::operator==(const Data::Note &rhs) const {
-	return timing == rhs.timing && position == rhs.position;
-}
-
-bool Data::Note::operator!=(const Data::Note &rhs) const {
-	return !(rhs == *this);
-}
-
-bool Data::Note::operator<(const Data::Note &rhs) const {
-	if (timing < rhs.timing) {
-        return true;
+    bool Note::operator==(const Note &rhs) const {
+        return timing == rhs.timing && position == rhs.position;
     }
-	if (rhs.timing < timing) {
-        return false;
+
+    bool Note::operator!=(const Note &rhs) const {
+        return !(rhs == *this);
     }
-	return position < rhs.position;
-}
 
-bool Data::Note::operator>(const Data::Note &rhs) const {
-	return rhs < *this;
-}
+    bool Note::operator<(const Note &rhs) const {
+        if (timing < rhs.timing) {
+            return true;
+        }
+        if (rhs.timing < timing) {
+            return false;
+        }
+        return position < rhs.position;
+    }
 
-bool Data::Note::operator<=(const Data::Note &rhs) const {
-	return !(rhs < *this);
-}
+    bool Note::operator>(const Note &rhs) const {
+        return rhs < *this;
+    }
 
-bool Data::Note::operator>=(const Data::Note &rhs) const {
-	return !(*this < rhs);
-}
-const unsigned int Data::Note::getPosition() const {
-    return position;    
-}
+    bool Note::operator<=(const Note &rhs) const {
+        return !(rhs < *this);
+    }
 
-const sf::Time& Data::Note::getTiming() const {
-    return timing;    
-}
+    bool Note::operator>=(const Note &rhs) const {
+        return !(*this < rhs);
+    }
+    unsigned int Note::getPosition() const {
+        return position;    
+    }
 
-const sf::Time& Data::Note::getLength() const {
-    return length;    
-}
+    const sf::Time& Note::getTiming() const {
+        return timing;    
+    }
 
-const unsigned int Data::Note::getTailPosition() const {
-    return tail_position;    
+    const sf::Time& Note::getLength() const {
+        return length;    
+    }
+
+    unsigned int Note::getTailPosition() const {
+        return tail_position;    
+    }
 }
diff --git a/src/Data/Note.hpp b/src/Data/Note.hpp
index 60f98cc..6ae4181 100644
--- a/src/Data/Note.hpp
+++ b/src/Data/Note.hpp
@@ -14,10 +14,10 @@ namespace Data {
         bool operator<=(const Note &rhs) const;
         bool operator>=(const Note &rhs) const;
 
-        const unsigned int getPosition() const;
+        unsigned int getPosition() const;
         const sf::Time& getTiming() const;
         const sf::Time& getLength() const;
-        const unsigned int getTailPosition() const;
+        unsigned int getTailPosition() const;
 
     private:
 
@@ -27,4 +27,4 @@ namespace Data {
         const unsigned int tail_position = 0;
 
     };
-};
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/src/Data/SongList.cpp b/src/Data/SongList.cpp
index 269ff95..4ed3f71 100644
--- a/src/Data/SongList.cpp
+++ b/src/Data/SongList.cpp
@@ -49,7 +49,7 @@ namespace Data {
                 fs::begin(folder),
                 fs::end(folder),
                 [](const fs::directory_entry& de) {
-                    de.path().extension() == ".memo" or
+                    return de.path().extension() == ".memo" or
                     de.path().extension() == ".memon";
                 }
             )
@@ -93,14 +93,14 @@ namespace Data {
             // .memo ?
             auto memo_files = getMemoFiles(song_folder);
             if (not memo_files.empty()) {
-                throw std::exception("jujube does not support .memo files for now ...");
+                throw std::invalid_argument("jujube does not support .memo files for now ...");
             } else {
                 throw std::invalid_argument("No valid file found in song folder");
             }
         }
     }
 
-    const std::vector<fs::path>& getMemoFiles(fs::path song_folder) {
+    const std::vector<fs::path> getMemoFiles(fs::path song_folder) {
         std::vector<fs::path> res;
         for (const auto& p : fs::directory_iterator(song_folder)) {
             if (p.path().extension() == ".memo") {
@@ -110,7 +110,7 @@ namespace Data {
         return res;
     }
 
-    const std::vector<fs::path>& getMemonFiles(fs::path song_folder) {
+    const std::vector<fs::path> getMemonFiles(fs::path song_folder) {
         std::vector<fs::path> res;
         for (const auto& p : fs::directory_iterator(song_folder)) {
             if (p.path().extension() == ".memon") {
diff --git a/src/Data/SongList.hpp b/src/Data/SongList.hpp
index fb9e70e..efceffc 100644
--- a/src/Data/SongList.hpp
+++ b/src/Data/SongList.hpp
@@ -46,6 +46,6 @@ namespace Data {
     // .memon files also accepted
     const std::vector<fs::path> getSongFolders();
     std::list<fs::path> recursiveSongSearch(fs::path song_or_pack);
-    const std::vector<fs::path>& getMemoFiles(fs::path song_folder);
-    const std::vector<fs::path>& getMemonFiles(fs::path song_folder);
+    const std::vector<fs::path> getMemoFiles(fs::path song_folder);
+    const std::vector<fs::path> getMemonFiles(fs::path song_folder);
 }
diff --git a/src/Resources/CoverAtlas.cpp b/src/Resources/CoverAtlas.cpp
index 066b5c0..2f139a8 100644
--- a/src/Resources/CoverAtlas.cpp
+++ b/src/Resources/CoverAtlas.cpp
@@ -23,7 +23,7 @@ sf::Sprite Textures::CoverAltas::at(const fs::path& path) const {
         index = 0;
     }
 
-    auto location = get_detailed_location(path_to_index.at(path));
+    auto location = get_detailed_location(index);
     sf::IntRect rect(location.column*256, location.row*256, 256, 256);
     sf::Sprite cover;
     cover.setTexture(textures.at(location.texture_index)->getTexture());
diff --git a/src/Resources/CoverAtlas.hpp b/src/Resources/CoverAtlas.hpp
index 78521b1..2341afd 100644
--- a/src/Resources/CoverAtlas.hpp
+++ b/src/Resources/CoverAtlas.hpp
@@ -18,7 +18,7 @@ namespace std {
             return std::hash<std::string>()(p.string());
         }
     };
-};
+}
 
 namespace Textures {
     
@@ -50,4 +50,4 @@ namespace Textures {
     };
 
     DetailedLocation get_detailed_location(unsigned int location);
-};
+}
diff --git a/src/Screens/MusicSelect/MusicSelect.cpp b/src/Screens/MusicSelect/MusicSelect.cpp
index d92e5e8..b2e3f78 100644
--- a/src/Screens/MusicSelect/MusicSelect.cpp
+++ b/src/Screens/MusicSelect/MusicSelect.cpp
@@ -37,9 +37,14 @@ void MusicSelect::Screen::select_chart(sf::RenderWindow& window) {
         // drawing the ribbon
         for (size_t panel = 0; panel < 12; panel++) {
             ribbon.at(panel)->draw(
-                *this,
+                resources,
                 window,
-                sf::FloatRect((panel%4)*150.f, (panel/4)*150.f, 150.f, 150.f)
+                sf::FloatRect(
+                    (panel%4)*150.f,
+                    (panel/4)*150.f,
+                    150.f,
+                    150.f
+                )
             );
         }
         window.display();
@@ -47,10 +52,4 @@ void MusicSelect::Screen::select_chart(sf::RenderWindow& window) {
 }
 
 void MusicSelect::Screen::handle_key(const sf::Event::KeyEvent& key_event) {
-    auto panel = key_mapping.key_to_button(key_event.code);
-    if (panel) {
-        if (Button::B2 <= *panel and *panel <= Button::B12) {
-            ribbon.at()
-        }
-    }
 }
diff --git a/src/Screens/MusicSelect/MusicSelect.hpp b/src/Screens/MusicSelect/MusicSelect.hpp
index 3efd3b4..d5a0133 100644
--- a/src/Screens/MusicSelect/MusicSelect.hpp
+++ b/src/Screens/MusicSelect/MusicSelect.hpp
@@ -33,4 +33,4 @@ namespace MusicSelect {
         KeyMapping key_mapping;
         void handle_key(const sf::Event::KeyEvent& key_event);
     };
-};
+}
diff --git a/src/Screens/MusicSelect/Panel.cpp b/src/Screens/MusicSelect/Panel.cpp
index c82522d..c433a30 100644
--- a/src/Screens/MusicSelect/Panel.cpp
+++ b/src/Screens/MusicSelect/Panel.cpp
@@ -4,6 +4,10 @@
 
 #include "MusicSelect.hpp"
 
+void MusicSelect::CategoryPanel::click(Screen& screen) {
+    
+}
+
 void MusicSelect::CategoryPanel::draw(Resources& resources, sf::RenderTarget& target, sf::FloatRect area) {
     sf::RectangleShape frame{{area.width*0.9f, area.height*0.9f}};
     frame.setFillColor(sf::Color::Black);
@@ -27,12 +31,22 @@ void MusicSelect::CategoryPanel::draw(Resources& resources, sf::RenderTarget& ta
     label_text.setString(this->label);
     label_text.setCharacterSize(24U);
     label_text.setFillColor(sf::Color::White);
-    auto bounds = label_text.getLocalBounds();
-    label_text.setOrigin(bounds.width / 2.f, bounds.height / 2.f);
-    if (bounds.height > bounds.width) {
-        label_text.setScale(area.height*0.8f / bounds.height, area.height*0.8f / bounds.height);
+    auto text_bounds = label_text.getLocalBounds();
+    label_text.setOrigin(text_bounds.width / 2.f, text_bounds.height / 2.f);
+    if (text_bounds.height > text_bounds.width) {
+        label_text.setScale(area.height*0.8f / text_bounds.height, area.height*0.8f / text_bounds.height);
     } else {
-        label_text.setScale(area.width*0.8f / bounds.width, area.width*0.8f / bounds.width);
+        label_text.setScale(area.width*0.8f / text_bounds.width, area.width*0.8f / text_bounds.width);
     }
     label_text.setPosition(area.left + area.width / 2.f, area.top + area.height / 2.f);
 }
+
+
+
+void MusicSelect::SongPanel::click(Screen& screen) {
+    
+}
+
+void MusicSelect::SongPanel::draw(Resources& resources, sf::RenderTarget& target, sf::FloatRect area) {
+    
+}
diff --git a/src/Screens/MusicSelect/Panel.hpp b/src/Screens/MusicSelect/Panel.hpp
index 9174ee3..3a98721 100644
--- a/src/Screens/MusicSelect/Panel.hpp
+++ b/src/Screens/MusicSelect/Panel.hpp
@@ -3,6 +3,7 @@
 #include <SFML/Graphics.hpp>
 #include <SFML/Window.hpp>
 
+#include "../../Data/SongList.hpp"
 #include "Resources.hpp"
 
 namespace MusicSelect {
@@ -28,7 +29,7 @@ namespace MusicSelect {
 
     class CategoryPanel final : public Panel {
     public:
-        CategoryPanel(const std::string& t_label) : label(t_label) {};
+        explicit CategoryPanel(const std::string& t_label) : label(t_label) {};
         void click(Screen& screen) override;
         void draw(Resources& resources, sf::RenderTarget& target, sf::FloatRect area) override;
     private:
@@ -37,7 +38,7 @@ namespace MusicSelect {
 
     class SongPanel final : public Panel {
     public:
-        SongPanel(const Data::Song& t_song) : song(t_song) {};
+        explicit SongPanel(const Data::Song& t_song) : song(t_song) {};
         void click(Screen& screen) override;
         void draw(Resources& resources, sf::RenderTarget& target, sf::FloatRect area) override;
     private:
diff --git a/src/Screens/MusicSelect/Ribbon.cpp b/src/Screens/MusicSelect/Ribbon.cpp
index c487765..948da5c 100644
--- a/src/Screens/MusicSelect/Ribbon.cpp
+++ b/src/Screens/MusicSelect/Ribbon.cpp
@@ -8,7 +8,7 @@
 MusicSelect::Ribbon MusicSelect::Ribbon::title_sort(const Data::SongList& song_list) {
     std::map<char,std::vector<Data::Song>> categories;
     for (const auto& song : song_list.songs) {
-        if (song.title.size > 0) {
+        if (song.title.size() > 0) {
             char letter = song.title[0];
             if ('A' <= letter and letter <= 'Z') {
                 categories[letter].push_back(song);
@@ -22,22 +22,25 @@ MusicSelect::Ribbon MusicSelect::Ribbon::title_sort(const Data::SongList& song_l
         }
     }
     Ribbon ribbon;
-    for (const auto& [letter, songs] : categories) {
-        std::vector<std::unique_ptr<Panel>> panels = {std::make_unique<CategoryPanel>(letter)};
+    for (auto& [letter, songs] : categories) {
+        std::vector<std::unique_ptr<Panel>> panels;
+        panels.emplace_back(
+            std::make_unique<CategoryPanel>(
+                std::string(1, letter)
+            )
+        );
         std::sort(songs.begin(), songs.end(), Data::Song::sort_by_title);
         for (const auto& song : songs) {
             panels.push_back(std::make_unique<SongPanel>(song));
         }
-        while (panels.size % 3 != 0) {
+        while (panels.size() % 3 != 0) {
             panels.push_back(std::make_unique<EmptyPanel>());
         }
-        for (size_t i = 0; i < panels.size; i += 3) {
-            std::array<std::unique_ptr<Panel>,3> column = {
-                std::move(panels[i]),
-                std::move(panels[i+1]),
-                std::move(panels[i+2])
-            };
-            ribbon.layout.push_back(column);
+        for (size_t i = 0; i < panels.size(); i += 3) {
+            ribbon.layout.emplace_back();
+            for (size_t j = 0; j < 3; j++) {
+                ribbon.layout.back()[j] = std::move(panels[i+j]);
+            }
         }
     }
     return ribbon;
diff --git a/src/Screens/MusicSelect/Ribbon.hpp b/src/Screens/MusicSelect/Ribbon.hpp
index 4586888..2b15ed7 100644
--- a/src/Screens/MusicSelect/Ribbon.hpp
+++ b/src/Screens/MusicSelect/Ribbon.hpp
@@ -8,7 +8,7 @@ namespace MusicSelect {
     // It can be sorted in a number of ways
     class Ribbon {
     public:
-        Ribbon();
+        Ribbon() = default;
         static Ribbon title_sort(const Data::SongList& song_list);
         static Ribbon test_sort();
         const auto& get_layout() {return layout;};