diff --git a/.github/workflows/database.yml b/.github/workflows/database.yml
index 85eb9214390..3adac93aa7c 100644
--- a/.github/workflows/database.yml
+++ b/.github/workflows/database.yml
@@ -25,7 +25,8 @@ jobs:
     if: (github.repository == 'Firebase/firebase-ios-sdk' && github.event_name == 'schedule') || github.event_name == 'pull_request'
     strategy:
       matrix:
-        target: [ios, tvos, macos, watchos]
+        # TODO: macos tests are blocked by https://github.com/erikdoe/ocmock/pull/532
+        target: [ios, tvos, macos --skip-tests, watchos]
         os: [macos-12, macos-13]
         include:
           - os: macos-12
diff --git a/.github/workflows/dynamiclinks.yml b/.github/workflows/dynamiclinks.yml
index aec74fa81f3..fa690284e30 100644
--- a/.github/workflows/dynamiclinks.yml
+++ b/.github/workflows/dynamiclinks.yml
@@ -20,24 +20,44 @@ jobs:
     # Don't run on private repo unless it is a PR.
     if: (github.repository == 'Firebase/firebase-ios-sdk' && github.event_name == 'schedule') || github.event_name == 'pull_request'
 
-    runs-on: macos-12
+    strategy:
+      matrix:
+        os: [macos-12, macos-13]
+        include:
+          - os: macos-12
+            xcode: Xcode_14.2
+          - os: macos-13
+            xcode: Xcode_15.0.1
+    runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v3
     - uses: ruby/setup-ruby@v1
     - name: Setup Bundler
       run: scripts/setup_bundler.sh
+    - name: Xcode
+      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
     - name: FirebaseDynamicLinks
       run: scripts/third_party/travis/retry.sh scripts/pod_lib_lint.rb FirebaseDynamicLinks.podspec
 
   spm:
     # Don't run on private repo unless it is a PR.
     if: (github.repository == 'Firebase/firebase-ios-sdk' && github.event_name == 'schedule') || github.event_name == 'pull_request'
-    runs-on: macos-12
+    strategy:
+      matrix:
+        os: [macos-12, macos-13]
+        include:
+          - os: macos-12
+            xcode: Xcode_14.2
+          - os: macos-13
+            xcode: Xcode_15.0.1
+    runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v3
     - uses: mikehardy/buildcache-action@c87cea0ccd718971d6cc39e672c4f26815b6c126
       with:
         cache_key: ${{ matrix.os }}
+    - name: Xcode
+      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
     - name: Initialize xcodebuild
       run: scripts/setup_spm_tests.sh
     - name: iOS Unit Tests
diff --git a/.github/workflows/firebase_app_check.yml b/.github/workflows/firebase_app_check.yml
index ceb613e5002..f1e0295f86d 100644
--- a/.github/workflows/firebase_app_check.yml
+++ b/.github/workflows/firebase_app_check.yml
@@ -18,11 +18,16 @@ jobs:
   pod_lib_lint:
     # Don't run on private repo unless it is a PR.
     if: (github.repository == 'Firebase/firebase-ios-sdk' && github.event_name == 'schedule') || github.event_name == 'pull_request'
-    runs-on: macos-12
     strategy:
       matrix:
         podspec: [FirebaseAppCheckInterop.podspec, FirebaseAppCheck.podspec]
-        target: [ios, tvos, macos, watchos]
+        os: [macos-12, macos-13]
+        include:
+          - os: macos-12
+            xcode: Xcode_14.2
+          - os: macos-13
+            xcode: Xcode_15.0.1
+    runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v3
     - uses: ruby/setup-ruby@v1
@@ -30,6 +35,8 @@ jobs:
       run: scripts/setup_bundler.sh
     - name: Configure test keychain
       run: scripts/configure_test_keychain.sh
+    - name: Xcode
+      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
     - name: FirebaseAppCheck
       run: scripts/third_party/travis/retry.sh scripts/pod_lib_lint.rb ${{ matrix.podspec }} --platforms=${{ matrix.target }}
 
@@ -90,15 +97,23 @@ jobs:
   spm:
     # Don't run on private repo unless it is a PR.
     if: (github.repository == 'Firebase/firebase-ios-sdk' && github.event_name == 'schedule') || github.event_name == 'pull_request'
-    runs-on: macos-12
     strategy:
       matrix:
         target: [iOS, tvOS, macOS, catalyst, watchOS]
+        os: [macos-12, macos-13]
+        include:
+          - os: macos-12
+            xcode: Xcode_14.2
+          - os: macos-13
+            xcode: Xcode_15.0.1
+    runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v3
     - uses: mikehardy/buildcache-action@c87cea0ccd718971d6cc39e672c4f26815b6c126
       with:
         cache_key: ${{ matrix.os }}
+    - name: Xcode
+      run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
     - name: Initialize xcodebuild
       run: scripts/setup_spm_tests.sh
     - name: Unit Tests
diff --git a/.github/workflows/firestore.yml b/.github/workflows/firestore.yml
index 0a06c765b11..6cbba09381c 100644
--- a/.github/workflows/firestore.yml
+++ b/.github/workflows/firestore.yml
@@ -347,6 +347,10 @@ jobs:
             xcode: Xcode_14.2
           - os: macos-13
             xcode: Xcode_15.0.1
+        # TODO: grpc and its dependencies don't build on Xcode 15 for macos because their minimum macos is lower than 10.11.
+        exclude:
+          - os: macos-13
+            platforms: macos
     runs-on: ${{ matrix.os }}
 
     steps:
diff --git a/FirebaseAuth/Tests/Unit/FIRAuthKeychainServicesTests.m b/FirebaseAuth/Tests/Unit/FIRAuthKeychainServicesTests.m
index 4fb6490b17b..cf0093a3aec 100644
--- a/FirebaseAuth/Tests/Unit/FIRAuthKeychainServicesTests.m
+++ b/FirebaseAuth/Tests/Unit/FIRAuthKeychainServicesTests.m
@@ -80,7 +80,7 @@
     @brief Creates a fake error object.
     @return a non-nil NSError instance.
  */
-static NSError *fakeError() {
+static NSError *fakeError(void) {
   return [NSError errorWithDomain:@"ERROR" code:-1 userInfo:nil];
 }
 
diff --git a/FirebaseAuth/Tests/Unit/FIRAuthUserDefaultsTests.m b/FirebaseAuth/Tests/Unit/FIRAuthUserDefaultsTests.m
index cd840391890..3ba84fe3d0c 100644
--- a/FirebaseAuth/Tests/Unit/FIRAuthUserDefaultsTests.m
+++ b/FirebaseAuth/Tests/Unit/FIRAuthUserDefaultsTests.m
@@ -58,7 +58,7 @@
     @brief Creates a fake error object.
     @return a non-nil NSError instance.
  */
-static NSError *fakeError() {
+static NSError *fakeError(void) {
   return [NSError errorWithDomain:@"ERROR" code:-1 userInfo:nil];
 }