https://bugs.gentoo.org/841734
--- a/core/CMakeLists.txt
+++ b/core/CMakeLists.txt
@@ -96,7 +96,7 @@ if(NOT ${CMAKE_SYSTEM_NAME} MATCHES "SunOS")
     -Werror=format-security compiler_error_format_security
   )
   if(${compiler_error_format_security})
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror=format-security")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wformat-security")
   endif()
 endif()
 
@@ -353,8 +353,8 @@ if(developer)
   add_definitions("-DDEVELOPER=1")
 endif()
 
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror -Wall")
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror -Wall")
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
 
 include(BareosSetVariableDefaults)
 option(ENABLE_BCONSOLE "Build bconsole binary" ON)