diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6775e3fff..f6e0e467f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -114,7 +114,20 @@ if(CMAKE_COMPILER_IS_GNUCC)
     set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -funroll-loops")
     set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -funroll-loops")
     add_definitions(-DBOOST_RESULT_OF_USE_DECLTYPE)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14 -Wall -pedantic -Wno-deprecated-declarations -Wno-unused-local-typedefs -Wno-unknown-pragmas")
+
+    set(STORM_CXX_STD_COMMAND "-std=c++14")
+    if (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 5.1)
+       message(STATUS "GCC Version is greater then 5.1, using -std=c++14")
+       set(STORM_CXX_STD_COMMAND "-std=c++14")
+    elseif(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.9.2)
+       message(WARNING "GCC Version is less then 4.9.2 - your compiler is probably too old for StoRM!")
+       set(STORM_CXX_STD_COMMAND "-std=c++1y")
+    else()
+       message(STATUS "GCC Version is between 4.9.2 and 5.1, using -std=c++1y")
+       set(STORM_CXX_STD_COMMAND "-std=c++1y")
+    endif()
+
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${STORM_CXX_STD_COMMAND} -Wall -pedantic -Wno-deprecated-declarations -Wno-unused-local-typedefs -Wno-unknown-pragmas")
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -pedantic -Wno-deprecated-declarations")
 
     # Turn on popcnt instruction if desired (yes by default)
@@ -362,6 +375,7 @@ find_package(CLN QUIET)
 
 if(CLN_FOUND)
     set(STORM_HAVE_CLN ON)
+    add_definitions(-DUSE_CLN_NUMBERS)
     message(STATUS "StoRM - Linking with CLN ${CLN_VERSION_STRING}")
     include_directories("${CLN_INCLUDE_DIR}")
     list(APPEND STORM_LINK_LIBRARIES ${CLN_LIBRARIES})