diff --git a/cmake/toolchain/systemtools.cmake b/cmake/toolchain/systemtools.cmake
index c3f03418235521d85bb19fd6a3034590ae2a1a8f..a8b324d46f9c7b9ec71d9ac564f1c713d6daa3f7 100644
--- a/cmake/toolchain/systemtools.cmake
+++ b/cmake/toolchain/systemtools.cmake
@@ -1,19 +1,19 @@
 #---define here the packages to be taken from the shystem for this OS and version
 if(${LCG_OS}${LCG_OSVERS} STREQUAL centos7)
 
-    set(LCG_system_packages bzip2 xz uuid curl motif                 jpeg glib)
+    set(LCG_system_packages bzip2 xz uuid curl motif                 jpeg glib flex bison)
 
 elseif(${LCG_OS}${LCG_OSVERS} STREQUAL slc6)
 
-    set(LCG_system_packages          uuid curl motif                 jpeg)
+    set(LCG_system_packages          uuid curl motif                 jpeg      flex bison)
 
 elseif(${LCG_OS}${LCG_OSVERS} STREQUAL ubuntu1604)
 
-    set(LCG_system_packages bzip2 xz uuid curl motif pkg_config      jpeg     )
+    set(LCG_system_packages bzip2 xz uuid curl motif pkg_config      jpeg      flex bison)
 
 elseif(${LCG_OS}${LCG_OSVERS} STREQUAL ubuntu1804)
 
-    set(LCG_system_packages bzip2 xz uuid curl motif pkg_config zlib jpeg glib)
+    set(LCG_system_packages bzip2 xz uuid curl motif pkg_config zlib jpeg glib flex bison)
 
 elseif(${LCG_OS}${LCG_OSVERS} STREQUAL mac1014)