diff --git a/configure b/configure
index 672b0412..78a47247 100755
--- a/configure
+++ b/configure
@@ -404,10 +404,17 @@ echo "${VERSION}"
 
 # Now we have the version string, we can build up the paths
 [ -z "${BINDIR_set}" ] && BINDIR="${PREFIX}/bin"
-[ -z "${LIBDIR_set}" ] && LIBDIR="${PREFIX}/lib/ct-ng-${VERSION}"
-[ -z "${DOCDIR_set}" ] && DOCDIR="${PREFIX}/share/doc/ct-ng-${VERSION}"
+[ -z "${LIBDIR_set}" ] && LIBDIR="${PREFIX}/lib"
+[ -z "${DOCDIR_set}" ] && DOCDIR="${PREFIX}/share/doc"
 [ -z "${MANDIR_set}" ] && MANDIR="${PREFIX}/share/man/man1"
 
+# Install support files in our own sub-dir, so as not to mangle (system)
+# files and dirs, but only if not --local
+if [ -z "${LOCAL_set}" ]; then
+    LIBDIR="${LIBDIR}/ct-ng-${VERSION}"
+    DOCDIR="${DOCDIR}/ct-ng-${VERSION}"
+fi
+
 # Check that install PATHs are absolute
 for p in BIN LIB DOC MAN; do
     var="${p}DIR"