diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4443999ba..e5cf1805e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -320,7 +320,7 @@ endif()
 
 # Configuring compilers
 if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -pedantic -Wuninitialized -Wunreachable-code -Wstrict-overflow=2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fPIC -fcolor-diagnostics -ftemplate-depth=1024 -Wno-unused-command-line-argument")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror -Wall -Wextra -pedantic -Wuninitialized -Wunreachable-code -Wunused-variable -Wstrict-overflow=2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fPIC -fcolor-diagnostics -ftemplate-depth=1024 -Wno-unused-command-line-argument")
 elseif(CMAKE_CXX_COMPILER_ID MATCHES "GNU")
   set(COLOR_FLAG "-fdiagnostics-color=auto")
   check_cxx_compiler_flag("-fdiagnostics-color=auto" HAS_COLOR_FLAG)
@@ -328,7 +328,7 @@ elseif(CMAKE_CXX_COMPILER_ID MATCHES "GNU")
     set(COLOR_FLAG "")
   endif()
   # using GCC
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -pedantic -Wuninitialized -Wunreachable-code -Wstrict-overflow=1 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 ${COLOR_FLAG} -fPIC -ftemplate-depth=1024")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror -Wall -Wextra -pedantic -Wuninitialized -Wunreachable-code -Wunused-variable -Wstrict-overflow=1 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 ${COLOR_FLAG} -fPIC -ftemplate-depth=1024")
   if(WIN32) # using mingw
     add_dependency_defines(-DWIN32)
     set(OPTIONAL_SOCKET_LIBS ws2_32 wsock32)