diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index b33f712..67c7f1b 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -21,7 +21,7 @@ If you wish to submit a PR, please be aware that:
 <br>
 
 ## Building and running the tests
-Testing is done using [Catch2], vendored in the respository at `vendor/catch.hpp`.
+Testing is done using [Catch2].
 
 ### Testing on Windows with Visual Studio
 
@@ -60,9 +60,12 @@ cd build-gcc-debug && ninja && ninja test               \
     && cd ..
 ```
 
-> ℹ&#xFE0F; Note: To ensure parity between single-header and regular versions of the library, 50% of the tests
+> ℹ&#xFE0F; To ensure parity between single-header and regular versions of the library, 50% of the tests
 will be compiled using one, and 50% with the other. Ensure you've regenerated toml.hpp before running tests.
 
+> ℹ&#xFE0F; Pass `-Duse_vendored_libs=false` to meson if you wish to use the system-installed version
+of Catch2 rather than the vendored one.
+
 <br>
 
 ## Testing with the [toml-test] suite
diff --git a/meson_options.txt b/meson_options.txt
index db4d088..885040c 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -10,3 +10,4 @@ option('ubsan_tests',			type: 'boolean', value: false)
 option('build_tt_encoder',		type: 'boolean', value: false,	description: 'Enable to build the toml-test encoder.')
 option('build_tt_decoder',		type: 'boolean', value: false,	description: 'Enable to build the toml-test decoder.')
 option('compile_library',		type: 'boolean', value: false,	description: 'Compile as a library')
+option('use_vendored_libs',		type: 'boolean', value: true,	description: 'Use the libs from the vendor dir when building tests.')
diff --git a/tests/lib_catch2.h b/tests/lib_catch2.h
index e70283a..9a04913 100644
--- a/tests/lib_catch2.h
+++ b/tests/lib_catch2.h
@@ -22,7 +22,15 @@
 #pragma warning(disable : 5105)
 #endif
 
+#if !defined(USE_VENDORED_LIBS) || USE_VENDORED_LIBS
 #include "../vendor/catch.hpp"
+#elif __has_include(<Catch2/single_include/catch2/catch.hpp>)
+#include <Catch2/single_include/catch2/catch.hpp>
+#elif __has_include(<catch2/catch.hpp>)
+#include <catch2/catch.hpp>
+#else
+#error Catch2 is missing!
+#endif
 
 #ifdef __clang__
 #pragma clang diagnostic pop
diff --git a/tests/meson.build b/tests/meson.build
index 3278fe0..a3f7d23 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -29,9 +29,10 @@ test_sources = [
 	'windows_compat.cpp'
 ]
 
-test_deps = [tomlplusplus_dep]
-
-fs = import('fs')
+test_deps = [ tomlplusplus_dep ]
+if not get_option('use_vendored_libs')
+	test_deps += dependency('catch2')
+endif
 
 #######################################################################################################################
 # fast math check
@@ -210,6 +211,10 @@ foreach cpp20 : cpp20_modes
 					test_args += '-DUSE_SINGLE_HEADER=1'
 				endif
 
+				if not get_option('use_vendored_libs')
+					test_args += '-DUSE_VENDORED_LIBS=0'
+				endif
+
 				test_executables += [[
 					test_name,
 					executable(
diff --git a/toml-test/README.md b/toml-test/README.md
index d2247d5..9c399ef 100644
--- a/toml-test/README.md
+++ b/toml-test/README.md
@@ -38,6 +38,9 @@ cd build_tt
 ninja && toml-test ./toml-test/tt_decoder && toml-test ./toml-test/tt_encoder --encoder
 ```
 
+> ℹ&#xFE0F; Pass `-Duse_vendored_libs=false` to meson if you wish to use the system-installed version
+of nlohmann/json rather than the vendored one.
+
 
 
 [toml-test]: https://github.com/BurntSushi/toml-test
diff --git a/toml-test/meson.build b/toml-test/meson.build
index 4e79e4d..8979e26 100644
--- a/toml-test/meson.build
+++ b/toml-test/meson.build
@@ -1,12 +1,19 @@
-tt_deps = [
-	tomlplusplus_dep
-]
+tt_deps = [ tomlplusplus_dep ]
+if not get_option('use_vendored_libs')
+	tt_deps += dependency('nlohmann_json', fallback: ['json', 'nlohmann_json_dep'])
+endif
+
+tt_args = []
+tt_args += devel_args
+if not get_option('use_vendored_libs')
+	tt_args += '-DUSE_VENDORED_LIBS=0'
+endif
 
 if get_option('build_tt_encoder')
 	executable(
 		'tt_encoder',
 		'tt_encoder.cpp',
-		cpp_args: devel_args,
+		cpp_args: tt_args,
 		dependencies: tt_deps
 	)
 endif
@@ -15,7 +22,7 @@ if get_option('build_tt_decoder')
 	executable(
 		'tt_decoder',
 		'tt_decoder.cpp',
-		cpp_args: devel_args,
+		cpp_args: tt_args,
 		dependencies: tt_deps
 	)
 endif
diff --git a/toml-test/tt.h b/toml-test/tt.h
index c7a0cee..58596cc 100644
--- a/toml-test/tt.h
+++ b/toml-test/tt.h
@@ -15,8 +15,17 @@
 #pragma warning(push, 0)
 #endif
 
-#define JSON_HAS_FILESYSTEM 0
+#define JSON_HAS_FILESYSTEM				 0
+#define JSON_HAS_EXPERIMENTAL_FILESYSTEM 0
+#if !defined(USE_VENDORED_LIBS) || USE_VENDORED_LIBS
 #include "../vendor/json.hpp"
+#elif __has_include(<json/single_include/nlohmann/json.hpp>)
+#include <json/single_include/nlohmann/json.hpp>
+#elif __has_include(<nlohmann/json.hpp>)
+#include <nlohmann/json.hpp>
+#else
+#error nlohmann/json is missing!
+#endif
 
 #include <string>
 #include <string_view>
diff --git a/vendor/README.md b/vendor/README.md
index a38255e..7576fb3 100644
--- a/vendor/README.md
+++ b/vendor/README.md
@@ -2,7 +2,6 @@
 
 The code files in this directory are third-party 'vendor' dependencies used by the various test applications.
 
-⚠&#xFE0F; They are **not** required for regular use of toml++. ⚠&#xFE0F;
-
-⚠&#xFE0F; They are not **not** `#included` anywhere in toml++. ⚠&#xFE0F;
+⚠&#xFE0F; They are **not** required for regular use of toml++.
 
+⚠&#xFE0F; They are **not** `#included` anywhere in toml++.