diff --git a/debian/preinst b/debian/preinst
index b657de5..3e8b0cd 100644
--- a/debian/preinst
+++ b/debian/preinst
@@ -2,17 +2,29 @@
 set -e
 
 if [ "$1" = "install" ] || [ "$1" = "upgrade" ]; then
+  msg=
   for d in bin lib lib32 lib64 libo32 lib64 sbin; do
-    if [ -d "$DPKG_ROOT/$d" ] && [ ! -L "$DPKG_ROOT/$d" ]; then
+    if [ -L "$DPKG_ROOT/$d" ]; then
+      if [ "$(readlink "$DPKG_ROOT/$d")" != "usr/$d" ]; then
+        msg="/$d is a symbolic link and not pointing at usr/$d exactly"
+      elif [ ! -d "$DPKG_ROOT/usr/$d" ]; then
+        msg="/$d is a dangling symbolic link"
+      fi
+      msg2="This is an unexpected situation. Cannot proceed with the upgrade"
+    elif [ -d "$DPKG_ROOT/$d" ]; then
+      msg="/$d is a directory, but should be a symbolic link"
+      msg2="Please install the usrmerge package to convert this system to merged-/usr"
+    fi
+    if [ -n "$msg" ]; then
       cat <<EOF
 
 
 ******************************************************************************
 *
-* The base-files package cannot be installed because this system has a
-* split /usr.
+* The base-files package cannot be installed because
+* $msg.
 *
-* Please install the usrmerge package to convert this system to merged-/usr.
+* $msg2.
 *
 * For more information please read https://wiki.debian.org/UsrMerge.
 *