diff --git a/cfg/gnu.cfg b/cfg/gnu.cfg
index 23aaf657071..fb998dee5ae 100644
--- a/cfg/gnu.cfg
+++ b/cfg/gnu.cfg
@@ -75,7 +75,6 @@
   <define name="__builtin_nan(str)" value="nan(str)"/>
   <define name="__builtin_nanf(str)" value="nanf(str)"/>
   <define name="__builtin_nanl(str)" value="nanl(str)"/>
-  <define name="__builtin_signbit(value)" value="signbit(value)"/>
   <define name="__extension__" value=""/>
   <define name="__typeof__(T)" value="typeof(T)"/>
   <define name="__glibc_unlikely(x)" value="(x)"/>