diff -Nru dpkg-1.18.10ubuntu1/debian/changelog dpkg-1.18.10ubuntu2/debian/changelog
--- dpkg-1.18.10ubuntu1/debian/changelog	2016-08-12 19:39:00.000000000 +0200
+++ dpkg-1.18.10ubuntu2/debian/changelog	2017-03-16 16:15:19.000000000 +0100
@@ -1,3 +1,11 @@
+dpkg (1.18.10ubuntu2) unstable; urgency=medium
+
+  * src/archives.c:
+    - fix incorrect checking of conffile when using --root=/dir
+      (LP: #1673247)
+
+ -- Michael Vogt <michael.vogt@ubuntu.com>  Thu, 16 Mar 2017 16:15:19 +0100
+
 dpkg (1.18.10ubuntu1) yakkety; urgency=medium
 
   * Merge from Debian testing; remaining Ubuntu changes:
diff -Nru dpkg-1.18.10ubuntu1/src/archives.c dpkg-1.18.10ubuntu2/src/archives.c
--- dpkg-1.18.10ubuntu1/src/archives.c	2016-07-08 01:36:47.000000000 +0200
+++ dpkg-1.18.10ubuntu2/src/archives.c	2017-03-16 16:15:12.000000000 +0100
@@ -656,7 +656,7 @@
 int
 tarobject(void *ctx, struct tar_entry *ti)
 {
-  static struct varbuf conffderefn, symlinkfn;
+  static struct varbuf conffderefn, symlinkfn, conffvb;
   const char *usename;
   struct filenamenode *usenode;
 
@@ -871,7 +871,11 @@
              conff = conff->next) {
           if (!conff->obsolete)
             continue;
-          if (stat(conff->name, &stabtmp)) {
+          varbuf_reset(&conffvb);
+          varbuf_add_str(&conffvb, instdir);
+          varbuf_add_str(&conffvb, conff->name);
+          varbuf_end_str(&conffvb);
+          if (stat(conffvb.buf, &stabtmp)) {
             if (errno == ENOENT || errno == ENOTDIR || errno == ELOOP)
               continue;
             else