diff --git a/cfg/gnu.cfg b/cfg/gnu.cfg
index 1c8d1597a7f..6135d7e35ef 100644
--- a/cfg/gnu.cfg
+++ b/cfg/gnu.cfg
@@ -247,7 +247,10 @@
   <!-- int __builtin_ffsl (long) -->
   <!-- int __builtin_ffsll (long long) -->
   <!-- int __builtin_clz (unsigned int x) -->
-  <function name="__builtin_popcount,__builtin_parity,__builtin_ffs,__builtin_ffsl,__builtin_ffsll,__builtin_clz">
+  <!-- int __builtin_ctz (unsigned int x) -->
+  <!-- int __builtin_ctzl (unsigned long x) -->
+  <!-- int __builtin_ctzll (unsigned long long x) -->
+  <function name="__builtin_popcount,__builtin_parity,__builtin_ffs,__builtin_ffsl,__builtin_ffsll,__builtin_clz,__builtin_ctz,__builtin_ctzl,__builtin_ctzll">
     <noreturn>false</noreturn>
     <returnValue type="int"/>
     <use-retval/>