diff --git a/FirebaseFirestore.podspec b/FirebaseFirestore.podspec
index f9e459a182b..f0ea55916a2 100644
--- a/FirebaseFirestore.podspec
+++ b/FirebaseFirestore.podspec
@@ -60,6 +60,7 @@ Google Cloud Firestore is a NoSQL document database built for automatic scaling,
   s.frameworks = 'MobileCoreServices', 'SystemConfiguration'
   s.library = 'c++'
   s.pod_target_xcconfig = {
+    'CLANG_CXX_LANGUAGE_STANDARD' => 'c++0x',
     'GCC_C_LANGUAGE_STANDARD' => 'c99',
     'GCC_PREPROCESSOR_DEFINITIONS' =>
       "FIRFirestore_VERSION=#{s.version} " +
diff --git a/Firestore/Example/Firestore.xcodeproj/project.pbxproj b/Firestore/Example/Firestore.xcodeproj/project.pbxproj
index 26cf2fffc4e..bfb19ac134c 100644
--- a/Firestore/Example/Firestore.xcodeproj/project.pbxproj
+++ b/Firestore/Example/Firestore.xcodeproj/project.pbxproj
@@ -543,7 +543,7 @@
 		B79CA87A1A01FC5329031C9B /* Pods_Firestore_FuzzTests_iOS.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Pods_Firestore_FuzzTests_iOS.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		B9C261C26C5D311E1E3C0CB9 /* query_test.cc */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.cpp.cpp; path = query_test.cc; sourceTree = "<group>"; };
 		BB92EB03E3F92485023F64ED /* Pods_Firestore_Example_iOS_Firestore_SwiftTests_iOS.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Pods_Firestore_Example_iOS_Firestore_SwiftTests_iOS.framework; sourceTree = BUILT_PRODUCTS_DIR; };
-		C8522DE226C467C54E6788D8 /* mutation_test.cc */ = {isa = PBXFileReference; includeInIndex = 1; path = mutation_test.cc; sourceTree = "<group>"; };
+		C8522DE226C467C54E6788D8 /* mutation_test.cc */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.cpp.cpp; path = mutation_test.cc; sourceTree = "<group>"; };
 		D3CC3DC5338DCAF43A211155 /* README.md */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = net.daringfireball.markdown; name = README.md; path = ../README.md; sourceTree = "<group>"; };
 		D5B2593BCB52957D62F1C9D3 /* perf_spec_test.json */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.json; path = perf_spec_test.json; sourceTree = "<group>"; };
 		DE03B2E91F2149D600A30B9C /* Firestore_IntegrationTests_iOS.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = Firestore_IntegrationTests_iOS.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -2095,7 +2095,6 @@
 				BUNDLE_LOADER = "$(TEST_HOST)";
 				CLANG_ANALYZER_NONNULL = YES;
 				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
-				CLANG_CXX_LANGUAGE_STANDARD = "gnu++14";
 				CLANG_WARN_BLOCK_CAPTURE_AUTORELEASING = YES;
 				CLANG_WARN_COMMA = YES;
 				CLANG_WARN_DOCUMENTATION_COMMENTS = YES;
@@ -2134,7 +2133,6 @@
 				BUNDLE_LOADER = "$(TEST_HOST)";
 				CLANG_ANALYZER_NONNULL = YES;
 				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
-				CLANG_CXX_LANGUAGE_STANDARD = "gnu++14";
 				CLANG_WARN_BLOCK_CAPTURE_AUTORELEASING = YES;
 				CLANG_WARN_COMMA = YES;
 				CLANG_WARN_DOCUMENTATION_COMMENTS = YES;
@@ -2338,7 +2336,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
-				CLANG_CXX_LANGUAGE_STANDARD = "gnu++0x";
+				CLANG_CXX_LANGUAGE_STANDARD = "c++0x";
 				CLANG_CXX_LIBRARY = "libc++";
 				CLANG_ENABLE_MODULES = YES;
 				CLANG_ENABLE_OBJC_ARC = YES;
@@ -2353,7 +2351,7 @@
 				"CODE_SIGN_IDENTITY[sdk=iphoneos*]" = "iPhone Developer";
 				COPY_PHASE_STRIP = NO;
 				ENABLE_TESTABILITY = YES;
-				GCC_C_LANGUAGE_STANDARD = gnu99;
+				GCC_C_LANGUAGE_STANDARD = c99;
 				GCC_DYNAMIC_NO_PIC = NO;
 				GCC_OPTIMIZATION_LEVEL = 0;
 				GCC_PREPROCESSOR_DEFINITIONS = (
@@ -2380,7 +2378,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
-				CLANG_CXX_LANGUAGE_STANDARD = "gnu++0x";
+				CLANG_CXX_LANGUAGE_STANDARD = "c++0x";
 				CLANG_CXX_LIBRARY = "libc++";
 				CLANG_ENABLE_MODULES = YES;
 				CLANG_ENABLE_OBJC_ARC = YES;
@@ -2395,7 +2393,7 @@
 				"CODE_SIGN_IDENTITY[sdk=iphoneos*]" = "iPhone Developer";
 				COPY_PHASE_STRIP = YES;
 				ENABLE_NS_ASSERTIONS = NO;
-				GCC_C_LANGUAGE_STANDARD = gnu99;
+				GCC_C_LANGUAGE_STANDARD = c99;
 				GCC_WARN_64_TO_32_BIT_CONVERSION = YES;
 				GCC_WARN_ABOUT_RETURN_TYPE = YES_ERROR;
 				GCC_WARN_UNDECLARED_SELECTOR = YES;
diff --git a/Firestore/Source/Core/FSTFirestoreClient.mm b/Firestore/Source/Core/FSTFirestoreClient.mm
index ecd288c4a0f..5b07b54912b 100644
--- a/Firestore/Source/Core/FSTFirestoreClient.mm
+++ b/Firestore/Source/Core/FSTFirestoreClient.mm
@@ -128,9 +128,10 @@ - (instancetype)initWithDatabaseInfo:(const DatabaseInfo &)databaseInfo
     _workerDispatchQueue = workerDispatchQueue;
 
     auto userPromise = std::make_shared<std::promise<User>>();
+    bool initialized = false;
 
     __weak __typeof__(self) weakSelf = self;
-    auto credentialChangeListener = [initialized = false, userPromise, weakSelf,
+    auto credentialChangeListener = [initialized, userPromise, weakSelf,
                                      workerDispatchQueue](User user) mutable {
       __typeof__(self) strongSelf = weakSelf;
       if (!strongSelf) return;