Plugin fails to resolve symbol in libc in older version of Mac than the build host

Hi all, hopefully someone can point me in the right direction here. Mac is not my primary OS, so this may be something simple for someone that knows Mac. I am building a plugin using a cmake project. I am building on Catalina. One of the user’s is using Mojave and is reporting that the plugin fails to load (both Au and VST3). For the VST3 library, this is the error that they are reporting to me. Does anyone have any ideas?:

Error loading /Library/Audio/Plug-Ins/VST3/Stochas.vst3/Contents/MacOS/Stochas: dlopen(/Library/Audio/Plug-Ins/VST3/Stochas.vst3/Contents/MacOS/Stochas, 262): Symbol not found: _objc_opt_class
Referenced from: /Library/Audio/Plug-Ins/VST3/Stochas.vst3/Contents/MacOS/Stochas (which was built for Mac OS X 10.15)
Expected in: /usr/lib/libobjc.A.dylib
in /Library/Audio/Plug-Ins/VST3/Stochas.vst3/Contents/MacOS/Stochas

I think you would need to lower the deployment target.

hints that the deployment target was set to 10.15 i.e Catalina. Try to set it to something older (I think 10.9 is a good compromise), choosing older might not allow you to use all new features of the SDKs.

You don’t need to change the Base SDK setting normally.

Thank you for the response Daniel. Pardon my ignorance, but any idea how can I change the deployment target in this situation, given that I am using cmake. As I said my mac knowledge is limited.

I haven‘t moved to cmake yet, but google finds this on the cmake docs: