diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..aa4cffa
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "external/log4cxx"]
+	path = external/log4cxx
+	url = https://github.com/apache/logging-log4cxx.git
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e7bd365..d0b7df3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -6,12 +6,16 @@ set(CMAKE_CXX_STANDARD 17)
 add_subdirectory(fluidsynth)
 add_subdirectory(magic_enum)
 add_subdirectory(argparse)
+add_subdirectory(external/log4cxx)
 
 file(GLOB_RECURSE sources src/*.cpp src/*.h)
 file(GLOB_RECURSE data resources/*)
 
 add_executable(tone-generator ${sources} ${data})
 
+target_include_directories(tone-generator PRIVATE $<TARGET_PROPERTY:log4cxx,INTERFACE_INCLUDE_DIRECTORIES>)
+
+target_link_libraries(tone-generator PRIVATE log4cxx)
 target_link_libraries(tone-generator PRIVATE libfluidsynth)
 target_link_libraries(tone-generator PRIVATE magic_enum::magic_enum)
-target_link_libraries(tone-generator PRIVATE argparse)
\ No newline at end of file
+target_link_libraries(tone-generator PRIVATE argparse)
diff --git a/README.md b/README.md
index 9f9ca8b..af5ea6d 100644
--- a/README.md
+++ b/README.md
@@ -21,13 +21,19 @@ make tone-generator
 - AB-CD and CD-AB are valid.
 - AA-CD and BA-CD are not valid.
 
-## Build with system packages?
+## System packages
 Requires the following packages (debian)
 
 ```
 sudo apt install libfluidsynth2 libfluidsynth-dev
 ```
+```
+liblog4cxx-dev/focal 0.10.0-15ubuntu2 amd64
+  Logging library for C++ (development files)
 
+liblog4cxx-doc/focal,focal 0.10.0-15ubuntu2 all
+  Documentation for log4cxx
+```
 
 May also need some soundfonts from:
 
diff --git a/external/log4cxx b/external/log4cxx
new file mode 160000
index 0000000..5354f9c
--- /dev/null
+++ b/external/log4cxx
@@ -0,0 +1 @@
+Subproject commit 5354f9cb739c348c05ae9938ebaded843f78fd78