diff --git a/BasiliskII/src/MacOSX/BasiliskII.xcodeproj/project.pbxproj b/BasiliskII/src/MacOSX/BasiliskII.xcodeproj/project.pbxproj
index 4bb52379..6b9cd01d 100644
--- a/BasiliskII/src/MacOSX/BasiliskII.xcodeproj/project.pbxproj
+++ b/BasiliskII/src/MacOSX/BasiliskII.xcodeproj/project.pbxproj
@@ -1064,7 +1064,7 @@
 				GCC_C_LANGUAGE_STANDARD = "compiler-default";
 				GCC_ENABLE_PASCAL_STRINGS = NO;
 				GCC_INLINES_ARE_PRIVATE_EXTERN = NO;
-				GCC_OPTIMIZATION_LEVEL = 3;
+				GCC_OPTIMIZATION_LEVEL = 0;
 				GCC_PREPROCESSOR_DEFINITIONS = (
 					"$(inherited)",
 					ENABLE_MACOSX_ETHERHELPER,
diff --git a/SheepShaver/src/MacOSX/SheepShaver_Xcode8.xcodeproj/project.pbxproj b/SheepShaver/src/MacOSX/SheepShaver_Xcode8.xcodeproj/project.pbxproj
index 086523f9..a686e0fb 100755
--- a/SheepShaver/src/MacOSX/SheepShaver_Xcode8.xcodeproj/project.pbxproj
+++ b/SheepShaver/src/MacOSX/SheepShaver_Xcode8.xcodeproj/project.pbxproj
@@ -1286,7 +1286,7 @@
 				GCC_ENABLE_PASCAL_STRINGS = NO;
 				GCC_ENABLE_TRIGRAPHS = NO;
 				GCC_INLINES_ARE_PRIVATE_EXTERN = NO;
-				GCC_OPTIMIZATION_LEVEL = 3;
+				GCC_OPTIMIZATION_LEVEL = 0;
 				GCC_PRECOMPILE_PREFIX_HEADER = NO;
 				GCC_PREFIX_HEADER = "";
 				GCC_PREPROCESSOR_DEFINITIONS = (