https://bugs.gentoo.org/907285
https://github.com/LMMS/lmms/issues/5884
https://src.fedoraproject.org/rpms/lmms/blob/rawhide/f/lmms-1.2.2_lib_suffix.patch
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -564,6 +564,9 @@ IF(USE_CCACHE)
     ENDIF()
 ENDIF()
 
+# pass LIB_SUFFIX
+add_definitions(-DLIB_SUFFIX="${LIB_SUFFIX}")
+
 # make sub-directories
 ADD_SUBDIRECTORY(cmake)
 ADD_SUBDIRECTORY(src)
--- a/src/core/PluginFactory.cpp
+++ b/src/core/PluginFactory.cpp
@@ -64,7 +64,7 @@ PluginFactory::PluginFactory()
 	//           plugins at "C:/Program Files/LMMS/plugins/"
 
 #ifndef LMMS_BUILD_WIN32
-	addRelativeIfExists("../lib/lmms"); // Installed
+	addRelativeIfExists("../lib" LIB_SUFFIX "/lmms"); // Installed
 #endif
 	addRelativeIfExists("plugins"); // Portable
 #ifdef PLUGIN_DIR // We may also have received a relative directory via a define