diff -U2 -r /var/lib/copr-rpmbuild/results/openmw-git/upstream-unpacked/Source0/openmw-master/components/shader/shadermanager.cpp /var/lib/copr-rpmbuild/results/openmw-git/srpm-unpacked/openmw-master.tar.bz2-extract/openmw-master/components/shader/shadermanager.cpp
--- /var/lib/copr-rpmbuild/results/openmw-git/upstream-unpacked/Source0/openmw-master/components/shader/shadermanager.cpp	2026-06-24 23:38:07.000000000 +0000
+++ /var/lib/copr-rpmbuild/results/openmw-git/srpm-unpacked/openmw-master.tar.bz2-extract/openmw-master/components/shader/shadermanager.cpp	2026-06-24 19:27:52.000000000 +0000
@@ -620,4 +620,5 @@
     void ShaderManager::setGlobalDefines(DefineMap& globalDefines)
     {
+        std::lock_guard<std::mutex> lock(mMutex);
         mGlobalDefines = globalDefines;
         // clear out linked dependencies - changing defines may make them obsolete