diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index e364223dd..6c2d37e70 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -4410,6 +4410,7 @@
 					"$(USER_LIBRARY_DIR)/Frameworks",
 				);
 				GCC_C_LANGUAGE_STANDARD = gnu11;
+				GCC_OPTIMIZATION_LEVEL = 3;
 				MACOSX_DEPLOYMENT_TARGET = 10.12;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
@@ -4578,6 +4579,7 @@
 					"$(inherited)",
 					"$(USER_LIBRARY_DIR)/Frameworks",
 				);
+				GCC_OPTIMIZATION_LEVEL = 3;
 				GCC_PREPROCESSOR_DEFINITIONS = "NDEBUG=1";
 				GCC_TREAT_IMPLICIT_FUNCTION_DECLARATIONS_AS_ERRORS = YES;
 				GCC_TREAT_INCOMPATIBLE_POINTER_TYPE_WARNINGS_AS_ERRORS = YES;
@@ -4625,6 +4627,7 @@
 				BUNDLE_LOADER = "$(TEST_HOST)";
 				CLANG_ENABLE_MODULES = YES;
 				COMBINE_HIDPI_IMAGES = YES;
+				GCC_OPTIMIZATION_LEVEL = fast;
 				INFOPLIST_FILE = "Clock SignalTests/Info.plist";
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/../Frameworks @loader_path/../Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = "TH.Clock-SignalTests";