diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 9a476c0..b560503 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -9,7 +9,7 @@ stages:
   stage: test
   script:
     - mkdir build && cd build
-    - cmake -DBUILD_TESTING=1 ..
+    - CXXFLAGS=-Werror cmake -DBUILD_TESTING=1 ..
     - make -j$(nproc)
     - broadwayd & CTEST_OUTPUT_ON_FAILURE=1 make test
 
diff --git a/src/cmake.cpp b/src/cmake.cpp
index ad8a420..c1327e7 100644
--- a/src/cmake.cpp
+++ b/src/cmake.cpp
@@ -151,7 +151,7 @@ boost::filesystem::path CMake::get_executable(const boost::filesystem::path &bui
     });
   }
 
-  boost::optional<size_t> best_match_size;
+  ssize_t best_match_size = -1;
   boost::filesystem::path best_match_executable;
 
   for(auto &cmake_executable : cmake_executables) {
@@ -163,7 +163,7 @@ boost::filesystem::path CMake::get_executable(const boost::filesystem::path &bui
           return maybe_executable;
         auto command_file_directory = command_file.parent_path();
         if(filesystem::file_in_path(file_path, command_file_directory)) {
-          auto size = static_cast<size_t>(std::distance(command_file_directory.begin(), command_file_directory.end()));
+          auto size = std::distance(command_file_directory.begin(), command_file_directory.end());
           if(size > best_match_size) {
             best_match_size = size;
             best_match_executable = maybe_executable;
@@ -182,7 +182,7 @@ boost::filesystem::path CMake::get_executable(const boost::filesystem::path &bui
       return maybe_executable;
     auto command_file_directory = command_file.parent_path();
     if(filesystem::file_in_path(file_path, command_file_directory)) {
-      auto size = static_cast<size_t>(std::distance(command_file_directory.begin(), command_file_directory.end()));
+      auto size = std::distance(command_file_directory.begin(), command_file_directory.end());
       if(size > best_match_size) {
         best_match_size = size;
         best_match_executable = maybe_executable;
diff --git a/src/meson.cpp b/src/meson.cpp
index 23bbe05..85e1dda 100644
--- a/src/meson.cpp
+++ b/src/meson.cpp
@@ -99,7 +99,7 @@ bool Meson::update_debug_build(const boost::filesystem::path &debug_build_path,
 boost::filesystem::path Meson::get_executable(const boost::filesystem::path &build_path, const boost::filesystem::path &file_path) {
   CompileCommands compile_commands(build_path);
 
-  boost::optional<size_t> best_match_size;
+  ssize_t best_match_size = -1;
   boost::filesystem::path best_match_executable;
   for(auto &command : compile_commands.commands) {
     auto command_file = filesystem::get_normal_path(command.file);
@@ -113,7 +113,7 @@ boost::filesystem::path Meson::get_executable(const boost::filesystem::path &bui
             return executable;
           auto command_file_directory = command_file.parent_path();
           if(filesystem::file_in_path(file_path, command_file_directory)) {
-            auto size = static_cast<size_t>(std::distance(command_file_directory.begin(), command_file_directory.end()));
+            auto size = std::distance(command_file_directory.begin(), command_file_directory.end());
             if(size > best_match_size) {
               best_match_size = size;
               best_match_executable = executable;
diff --git a/src/source.cpp b/src/source.cpp
index 768a86f..eb4f547 100644
--- a/src/source.cpp
+++ b/src/source.cpp
@@ -233,7 +233,7 @@ Source::View::View(const boost::filesystem::path &file_path, const Glib::RefPtr<
         --line_end;
       bool lines_commented = true;
       bool extra_spaces = true;
-      boost::optional<int> min_indentation;
+      int min_indentation = std::numeric_limits<int>::max();
       for(auto line = line_start; line <= line_end; ++line) {
         auto iter = get_buffer()->get_iter_at_line(line);
         bool line_added = false;
@@ -279,8 +279,7 @@ Source::View::View(const boost::filesystem::path &file_path, const Glib::RefPtr<
         if(line_added) {
           lines_commented &= line_commented;
           extra_spaces &= extra_space;
-          if(!min_indentation || indentation < min_indentation)
-            min_indentation = indentation;
+          min_indentation = std::min(min_indentation, indentation);
         }
       }
       if(lines.size()) {
@@ -288,7 +287,8 @@ Source::View::View(const boost::filesystem::path &file_path, const Glib::RefPtr<
         get_buffer()->begin_user_action();
         for(auto &line : lines) {
           auto iter = get_buffer()->get_iter_at_line(line);
-          iter.forward_chars(min_indentation.value_or(0));
+          if(min_indentation != std::numeric_limits<int>::max())
+            iter.forward_chars(min_indentation);
           if(lines_commented) {
             auto end_iter = iter;
             end_iter.forward_chars(comment_characters.size() + static_cast<int>(extra_spaces));