diff --git a/cmake/GtsamTesting.cmake b/cmake/GtsamTesting.cmake
index 5e2c84b60..25d091e50 100644
--- a/cmake/GtsamTesting.cmake
+++ b/cmake/GtsamTesting.cmake
@@ -112,10 +112,11 @@ if(NOT DEFINED PROCESSOR_COUNT)
 
 	# Mac:
 	if(APPLE)
-		find_program(cmd_sysctl "sysctl")
-		if(cmd_sysctl)
-			execute_process(COMMAND ${cmd_sysctl} -n hw.ncpu OUTPUT_VARIABLE info)
-			string(STRIP ${info} PROCESSOR_COUNT)
+		find_program(cmd_sys_pro "system_profiler")
+		if(cmd_sys_pro)
+			execute_process(COMMAND ${cmd_sys_pro} OUTPUT_VARIABLE info)
+			string(REGEX REPLACE "^.*Total Number Of Cores: ([0-9]+).*$" "\\1"
+					PROCESSOR_COUNT "${info}")
 		endif()
 	endif()