--- a/cmake/VERSION.cmake
+++ b/cmake/VERSION.cmake
@@ -3,7 +3,7 @@
 set(PROJECT_VERSION_MAJOR "6")
 set(PROJECT_VERSION_MINOR "0")
 set(PROJECT_VERSION_PATCH "0")
-set(PROJECT_VERSION_EXTRA "-rc1")
+set(PROJECT_VERSION_EXTRA "_rc1")
 set(PROJECT_GENERATION "${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}")
 set(PROJECT_GENERATION_SHORT "${PROJECT_VERSION_MAJOR}${PROJECT_VERSION_MINOR}")
 set(PROJECT_VERSION "${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}.${PROJECT_VERSION_PATCH}${PROJECT_VERSION_EXTRA}")