diff --git a/mac/Audacity.xcodeproj/project.pbxproj b/mac/Audacity.xcodeproj/project.pbxproj
index 108316fec..8050a6959 100644
--- a/mac/Audacity.xcodeproj/project.pbxproj
+++ b/mac/Audacity.xcodeproj/project.pbxproj
@@ -9623,6 +9623,7 @@
 				GCC_PREPROCESSOR_DEFINITIONS = (
 					"$(GCC_PREPROCESSOR_DEFINITIONS_QUOTED_FOR_TARGET_1)",
 					"BUILDING_AUDACITY=1",
+					"HAVE_MLOCK=1",
 					"$(GCC_PREPROCESSOR_DEFINITIONS_QUOTED_FOR_TARGET_1)",
 				);
 				GCC_PREPROCESSOR_DEFINITIONS_QUOTED_FOR_TARGET_1 = "AUDACITY_DLL_API=\"\"";
@@ -9959,6 +9960,7 @@
 				GCC_PREPROCESSOR_DEFINITIONS = (
 					"$(GCC_PREPROCESSOR_DEFINITIONS_QUOTED_FOR_TARGET_1)",
 					"BUILDING_AUDACITY=1",
+					"HAVE_MLOCK=1",
 					"$(GCC_PREPROCESSOR_DEFINITIONS_QUOTED_FOR_TARGET_1)",
 				);
 				GCC_PREPROCESSOR_DEFINITIONS_QUOTED_FOR_TARGET_1 = "AUDACITY_DLL_API=\"\"";
@@ -10388,6 +10390,7 @@
 				GCC_PREPROCESSOR_DEFINITIONS = (
 					"$(GCC_PREPROCESSOR_DEFINITIONS_QUOTED_FOR_TARGET_1)",
 					"BUILDING_AUDACITY=1",
+					"HAVE_MLOCK=1",
 					"$(GCC_PREPROCESSOR_DEFINITIONS_QUOTED_FOR_TARGET_1)",
 				);
 				GCC_PREPROCESSOR_DEFINITIONS_QUOTED_FOR_TARGET_1 = "AUDACITY_DLL_API=\"\"";
@@ -10848,6 +10851,7 @@
 				GCC_PREPROCESSOR_DEFINITIONS = (
 					"$(GCC_PREPROCESSOR_DEFINITIONS_QUOTED_FOR_TARGET_1)",
 					"BUILDING_AUDACITY=1",
+					"HAVE_MLOCK=1",
 					"$(GCC_PREPROCESSOR_DEFINITIONS_QUOTED_FOR_TARGET_1)",
 				);
 				GCC_PREPROCESSOR_DEFINITIONS_QUOTED_FOR_TARGET_1 = "AUDACITY_DLL_API=\"\"";