diff --git a/libcthreads.spec b/libcthreads.spec
index b3dcc7f..a6b60d7 100644
--- a/libcthreads.spec
+++ b/libcthreads.spec
@@ -66,6 +66,7 @@ applications that want to make use of libcthreads.
 autoreconf -fi
 echo "V_%version { global: *; };" >v.sym
 %configure --disable-static LDFLAGS="-Wl,--version-script=$PWD/v.sym"
+grep '  local' config.log && exit 1
 %make_build
 
 %install