diff --git a/src/gcc_wrapper.cpp b/src/gcc_wrapper.cpp
index 42127c0..dfd76ff 100644
--- a/src/gcc_wrapper.cpp
+++ b/src/gcc_wrapper.cpp
@@ -21,13 +21,14 @@
 
 #include "debug_utils.hpp"
 #include "sys_utils.hpp"
+#include "unicode_utils.hpp"
 
 #include <stdexcept>
 
 namespace bcache {
 namespace {
 bool is_source_file(const std::string& arg) {
-  const auto ext = file::get_extension(arg);
+  const auto ext = lower_case(file::get_extension(arg));
   return ((ext == ".cpp") || (ext == ".cc") || (ext == ".cxx") || (ext == ".c"));
 }
 
@@ -67,7 +68,7 @@ gcc_wrapper_t::gcc_wrapper_t(cache_t& cache) : program_wrapper_t(cache) {
 
 bool gcc_wrapper_t::can_handle_command(const std::string& program_exe) {
   // Is this the right compiler?
-  const auto cmd = file::get_file_part(program_exe, false);
+  const auto cmd = lower_case(file::get_file_part(program_exe, false));
   return (cmd.find("gcc") != std::string::npos) || (cmd.find("g++") != std::string::npos) ||
          (cmd.find("clang++") != std::string::npos) || (cmd == "clang");
 }
diff --git a/src/ghs_wrapper.cpp b/src/ghs_wrapper.cpp
index 78b5b54..732b845 100644
--- a/src/ghs_wrapper.cpp
+++ b/src/ghs_wrapper.cpp
@@ -20,7 +20,7 @@
 #include "ghs_wrapper.hpp"
 
 #include "file_utils.hpp"
-#include "hasher.hpp"
+#include "unicode_utils.hpp"
 
 #include <stdexcept>
 
@@ -30,7 +30,7 @@ ghs_wrapper_t::ghs_wrapper_t(cache_t& cache) : gcc_wrapper_t(cache) {
 
 bool ghs_wrapper_t::can_handle_command(const std::string& program_exe) {
   // Is this the right compiler?
-  const auto cmd = file::get_file_part(program_exe, false);
+  const auto cmd = lower_case(file::get_file_part(program_exe, false));
   return (cmd.find("ccarm") != std::string::npos) || (cmd.find("cxarm") != std::string::npos) ||
          (cmd.find("ccthumb") != std::string::npos) || (cmd.find("cxthumb") != std::string::npos) ||
          (cmd.find("ccintarm") != std::string::npos) || (cmd.find("cxintarm") != std::string::npos);
diff --git a/src/main.cpp b/src/main.cpp
index 646f0e8..e8efa9f 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -26,6 +26,7 @@
 #include "program_wrapper.hpp"
 #include "string_list.hpp"
 #include "sys_utils.hpp"
+#include "unicode_utils.hpp"
 
 #include <iostream>
 #include <memory>
@@ -58,7 +59,7 @@ bcache::string_list_t get_lua_paths(const bcache::cache_t& cache) {
 }
 
 bool is_lua_script(const std::string& script_path) {
-  return (bcache::file::get_extension(script_path) == ".lua");
+  return (bcache::lower_case(bcache::file::get_extension(script_path)) == ".lua");
 }
 
 [[noreturn]] void clear_cache_and_exit() {
diff --git a/src/msvc_wrapper.cpp b/src/msvc_wrapper.cpp
index b9373f3..20b8185 100644
--- a/src/msvc_wrapper.cpp
+++ b/src/msvc_wrapper.cpp
@@ -21,13 +21,14 @@
 
 #include "debug_utils.hpp"
 #include "sys_utils.hpp"
+#include "unicode_utils.hpp"
 
 #include <stdexcept>
 
 namespace bcache {
 namespace {
 bool is_source_file(const std::string& arg) {
-  const auto ext = file::get_extension(arg);
+  const auto ext = lower_case(file::get_extension(arg));
   return ((ext == ".cpp") || (ext == ".cc") || (ext == ".cxx") || (ext == ".c"));
 }
 
@@ -73,7 +74,7 @@ msvc_wrapper_t::msvc_wrapper_t(cache_t& cache) : program_wrapper_t(cache) {
 
 bool msvc_wrapper_t::can_handle_command(const std::string& program_exe) {
   // Is this the right compiler?
-  const auto cmd = file::get_file_part(program_exe, false);
+  const auto cmd = lower_case(file::get_file_part(program_exe, false));
   return (cmd == "cl");
 }