diff --git a/ao.m4 b/ao.m4
index 20f43a257727f56c2c4f04164dce5b477ae574f9..c8f60388252fd47b55026b151bcb99c399af7f40 100644
--- a/ao.m4
+++ b/ao.m4
@@ -18,7 +18,7 @@ AC_ARG_ENABLE(aotest, [  --disable-aotest       Do not try to compile and run a
     AO_LIBS="-L$ao_prefix/lib"
   fi
 
-  AO_LIBS="$AO_LIBS -lao"
+  AO_LIBS="$AO_LIBS -lao -ldl"
 
   AC_MSG_CHECKING(for ao)
   no_ao=""