diff --git a/tests/benchmarks/CMakeLists.txt b/tests/benchmarks/CMakeLists.txt
index 1e835d120..4d7265145 100644
--- a/tests/benchmarks/CMakeLists.txt
+++ b/tests/benchmarks/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.11...3.14)
+cmake_minimum_required(VERSION 3.14)
 project(JSON_Benchmarks LANGUAGES CXX)
 
 # set compiler flags
@@ -6,21 +6,22 @@ if((CMAKE_CXX_COMPILER_ID MATCHES GNU) OR (CMAKE_CXX_COMPILER_ID MATCHES Clang))
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -flto -DNDEBUG -O3")
 endif()
 
-# configure Google Benchmarks
+# configure Google Benchmark; a fixed release, so that results stay comparable
+set(JSON_GOOGLE_BENCHMARK_VERSION 1.9.5)
 include(FetchContent)
-FetchContent_Declare(
-    benchmark
-    GIT_REPOSITORY https://github.com/google/benchmark.git
-    GIT_TAG origin/main
-    GIT_SHALLOW TRUE
-)
 
-FetchContent_GetProperties(benchmark)
-if(NOT benchmark_POPULATED)
-    FetchContent_Populate(benchmark)
-    set(BENCHMARK_ENABLE_TESTING OFF CACHE INTERNAL "" FORCE)
-    add_subdirectory(${benchmark_SOURCE_DIR} ${benchmark_BINARY_DIR})
-endif()
+# only the library is needed; -Werror would break the pinned release as soon as
+# a newer compiler adds a warning
+set(BENCHMARK_ENABLE_TESTING OFF CACHE BOOL "" FORCE)
+set(BENCHMARK_ENABLE_INSTALL OFF CACHE BOOL "" FORCE)
+set(BENCHMARK_ENABLE_WERROR OFF CACHE BOOL "" FORCE)
+
+FetchContent_Declare(benchmark
+    URL https://github.com/google/benchmark/archive/refs/tags/v${JSON_GOOGLE_BENCHMARK_VERSION}.tar.gz
+    URL_HASH SHA256=9631341c82bac4a288bef951f8b26b41f69021794184ece969f8473977eaa340
+    DOWNLOAD_EXTRACT_TIMESTAMP TRUE
+)
+FetchContent_MakeAvailable(benchmark)
 
 # download test data
 set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/../../cmake ${CMAKE_MODULE_PATH})
diff --git a/tests/benchmarks/README.md b/tests/benchmarks/README.md
index a4e095ae0..aaf5abe46 100644
--- a/tests/benchmarks/README.md
+++ b/tests/benchmarks/README.md
@@ -23,10 +23,12 @@ The input files are those of [nativejson-benchmark](https://github.com/miloyip/n
 
 ## Requirements
 
-- CMake 3.11 or later, a C++11 compiler, and Ninja for the `make` target.
-- Network access on the first configure: CMake fetches Google Benchmark and downloads the
-  [test data](https://github.com/nlohmann/json_test_data) into the build directory. To reuse a download, pass
-  `-DJSON_TestDataDirectory=<build directory>/test_files`.
+- CMake 3.14 or later, a C++11 compiler, and Ninja for the `make` target.
+- Network access on the first configure: CMake downloads Google Benchmark and the
+  [test data](https://github.com/nlohmann/json_test_data) into the build directory. To reuse a download of the test
+  data, pass `-DJSON_TestDataDirectory=<build directory>/test_files`.
+- Google Benchmark is pinned to a release (1.9.5), so that results from different days stay comparable. To update it,
+  change `JSON_GOOGLE_BENCHMARK_VERSION` and the archive's `URL_HASH` in `CMakeLists.txt` together.
 - The benchmarks include `single_include/nlohmann/json.hpp`, so run `make amalgamate` after changing anything in
   `include/`.
 
@@ -99,8 +101,8 @@ build-venv/bin/pip install numpy scipy
 build-venv/bin/python build-current/_deps/benchmark-src/tools/compare.py -a benchmarks build-baseline/results.json build-current/results.json
 ```
 
-The tool's own `tools/requirements.txt` pins the newest NumPy and SciPy, which may need a newer Python than yours;
-unpinned versions work as well. In its output:
+The tool's own `tools/requirements.txt` pins NumPy and SciPy versions that need Python 3.11 or later; with an older
+Python, unpinned versions work as well. In its output:
 
 - the `Time` and `CPU` columns are relative changes: `-0.35` means 35% faster, `+0.10` means 10% slower;
 - `_pvalue` lines report a Mann-Whitney U test of whether the two versions differ. It needs at least 9