diff --git a/.github/workflows/bazel.yml b/.github/workflows/bazel.yml
index ea231a3c..d9668779 100644
--- a/.github/workflows/bazel.yml
+++ b/.github/workflows/bazel.yml
@@ -4,6 +4,9 @@ on:
   push: {}
   pull_request: {}
 
+env:
+  CMAKE_GENERATOR: Ninja
+
 jobs:
   build_and_test_default:
     name: bazel.${{ matrix.os }}
diff --git a/.github/workflows/build-and-test-min-cmake.yml b/.github/workflows/build-and-test-min-cmake.yml
index 25099842..2b56e6a6 100644
--- a/.github/workflows/build-and-test-min-cmake.yml
+++ b/.github/workflows/build-and-test-min-cmake.yml
@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [ main ]
 
+env:
+  CMAKE_GENERATOR: Ninja
+
 jobs:
   job:
     name: ${{ matrix.os }}.min-cmake
diff --git a/.github/workflows/build-and-test-perfcounters.yml b/.github/workflows/build-and-test-perfcounters.yml
index 319d42d8..d12d020e 100644
--- a/.github/workflows/build-and-test-perfcounters.yml
+++ b/.github/workflows/build-and-test-perfcounters.yml
@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [ main ]
 
+env:
+  CMAKE_GENERATOR: Ninja
+
 jobs:
   job:
     # TODO(dominic): Extend this to include compiler and set through env: CC/CXX.
diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index 8394d101..8f061e14 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [ main ]
 
+env:
+  CMAKE_GENERATOR: Ninja
+
 jobs:
   # TODO: add 32-bit builds (g++ and clang++) for ubuntu
   #   (requires g++-multilib and libc6:i386)
@@ -23,6 +26,10 @@ jobs:
         lib: ['shared', 'static']
 
     steps:
+      - name: Install dependencies (macos)
+        if: runner.os == 'macOS'
+        run: brew install ninja
+
       - uses: actions/checkout@v4
 
       - name: build
diff --git a/.github/workflows/clang-format-lint.yml b/.github/workflows/clang-format-lint.yml
index de3e5912..39565167 100644
--- a/.github/workflows/clang-format-lint.yml
+++ b/.github/workflows/clang-format-lint.yml
@@ -3,6 +3,9 @@ on:
   push: {}
   pull_request: {}
 
+env:
+  CMAKE_GENERATOR: Ninja
+
 jobs:
   job:
     name: check-clang-format
diff --git a/.github/workflows/clang-tidy-lint.yml b/.github/workflows/clang-tidy-lint.yml
index e38153b8..b3a8964c 100644
--- a/.github/workflows/clang-tidy-lint.yml
+++ b/.github/workflows/clang-tidy-lint.yml
@@ -4,6 +4,9 @@ on:
   push: {}
   pull_request: {}
 
+env:
+  CMAKE_GENERATOR: Ninja
+
 jobs:
   job:
     name: run-clang-tidy
diff --git a/.github/workflows/doxygen.yml b/.github/workflows/doxygen.yml
index 40c1cb4e..bcab2c23 100644
--- a/.github/workflows/doxygen.yml
+++ b/.github/workflows/doxygen.yml
@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [main]
 
+env:
+  CMAKE_GENERATOR: Ninja
+
 jobs:
   build-and-deploy:
     name: Build HTML documentation
diff --git a/.github/workflows/pre-commit.yml b/.github/workflows/pre-commit.yml
index 8b217e98..d56dde93 100644
--- a/.github/workflows/pre-commit.yml
+++ b/.github/workflows/pre-commit.yml
@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [ main ]
 
+env:
+  CMAKE_GENERATOR: Ninja
+
 jobs:
   pre-commit:
     runs-on: ubuntu-latest
diff --git a/.github/workflows/sanitizer.yml b/.github/workflows/sanitizer.yml
index 9eb99475..05c265bb 100644
--- a/.github/workflows/sanitizer.yml
+++ b/.github/workflows/sanitizer.yml
@@ -5,6 +5,7 @@ on:
   pull_request: {}
 
 env:
+  CMAKE_GENERATOR: Ninja
   UBSAN_OPTIONS: "print_stacktrace=1"
 
 jobs:
@@ -18,11 +19,6 @@ jobs:
         sanitizer: ['asan', 'ubsan', 'tsan', 'msan']
 
     steps:
-    - name: Installing build dependencies
-      run: |
-        sudo apt update
-        sudo apt install ninja-build
-
     - uses: actions/checkout@v4
 
     - name: configure msan env
diff --git a/.github/workflows/test_bindings.yml b/.github/workflows/test_bindings.yml
index b6ac9be8..df02c9f1 100644
--- a/.github/workflows/test_bindings.yml
+++ b/.github/workflows/test_bindings.yml
@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [main]
 
+env:
+  CMAKE_GENERATOR: Ninja
+
 jobs:
   python_bindings:
     name: Test GBM Python ${{ matrix.python-version }} bindings on ${{ matrix.os }}
diff --git a/.github/workflows/wheels.yml b/.github/workflows/wheels.yml
index 0569dcc9..d24db9c7 100644
--- a/.github/workflows/wheels.yml
+++ b/.github/workflows/wheels.yml
@@ -6,6 +6,9 @@ on:
     types:
       - published
 
+env:
+  CMAKE_GENERATOR: Ninja
+
 jobs:
   build_sdist:
     name: Build source distribution