Unable to make unit tests due to missing pthread.h

I have been following this guide: Unit testing - Debugging and testing | Mbed OS 6 Documentation for getting a unit testing system set up. However, “making” the makefile comes up with an error that I can’t seem to fix.

I’m on windows 10. Built with Cmake and tried to make using “make”. The error seems to be a missing header file pthread.h. But I’m not sure why it’s missing and how to get it to make without it.

Console output
PS C:\Users\Tijn\Mbed Programs\ExternalFlash_POC\mbed-os\UNITTESTS\build> make
[  0%] Building CXX object CMakeFiles/connectivity-cellular-tests-UNITTESTS-framework-device-cellularstatemachine.MbedOS.dir/3fecb2fd01cb6bda027c2eb977a99e78/framework/device/CellularStateMachine.cpp.obj
In file included from c:\users\tijn\mbedpr~1\extern~1\mbed-os\events\include\events\equeue.h:28:0,
                 from c:\users\tijn\mbedpr~1\extern~1\mbed-os\events\include\events\eventqueue.h:21,
                 from c:\users\tijn\mbedpr~1\extern~1\mbed-os\connec~1\cellular\include\cellular\framew~1\device\cellularstatemachine.h:20,
                 from C:\Users\Tijn\Mbed Programs\ExternalFlash_POC\mbed-os\connectivity\cellular\source\framework\device\CellularStateMachine.cpp:18:
c:\users\tijn\mbedpr~1\extern~1\mbed-os\events\include\events\internal\equeue_platform.h:50:21: fatal error: pthread.h: No such file or directory
 #include <pthread.h>
                     ^
compilation terminated.
make[2]: *** [CMakeFiles\connectivity-cellular-tests-UNITTESTS-framework-device-cellularstatemachine.MbedOS.dir\build.make:76: CMakeFiles/connectivity-cellular-tests-UNITTESTS-framework-device-cellularstatemachine.MbedOS.dir/3fecb2fd01cb6bda027c2eb977a99e78/framework/device/CellularStateMachine.cpp.obj] Error 1
make[1]: *** [CMakeFiles\Makefile2:462: CMakeFiles/connectivity-cellular-tests-UNITTESTS-framework-device-cellularstatemachine.MbedOS.dir/all] Error 2
make: *** [Makefile:145: all] Error 2
PS C:\Users\Tijn\Mbed Programs\ExternalFlash_POC\mbed-os\UNITTESTS\build>

Does anybody more experienced with gtests/cmake have an idea on how to fix this?