diff --git a/src/engine/client/client.cpp b/src/engine/client/client.cpp
index cb7737486..fee56a174 100644
--- a/src/engine/client/client.cpp
+++ b/src/engine/client/client.cpp
@@ -4589,7 +4589,10 @@ int main(int argc, const char **argv)
 	pKernel->RegisterInterface(pClient, false);
 	pClient->RegisterInterfaces();
 
-	dbg_assert_set_handler([pClient](const char *pMsg) {
+	const std::thread::id MainThreadId = std::this_thread::get_id();
+	dbg_assert_set_handler([MainThreadId, pClient](const char *pMsg) {
+		if(MainThreadId != std::this_thread::get_id())
+			return;
 		char aVersionStr[128];
 		if(os_version_str(aVersionStr, sizeof(aVersionStr)))
 			str_copy(aVersionStr, "unknown");