diff --git a/winsup/cygwin/Makefile.am b/winsup/cygwin/Makefile.am
index ea9d4b382..a2e673c13 100644
--- a/winsup/cygwin/Makefile.am
+++ b/winsup/cygwin/Makefile.am
@@ -32,8 +32,8 @@ newlib_build=$(target_builddir)/newlib
 # installed there by newlib.
 #
 
-toollibdir=$(prefix)/$(target_alias)/lib
-toolincludedir=$(prefix)/$(target_alias)/include
+toollibdir=$(tooldir)/lib
+toolincludedir=$(tooldir)/include
 
 # Parameters used in building the cygwin.dll.