diff --git a/0001-Fix-seed-chunker-discriminator-not-set-78.patch b/0001-Fix-seed-chunker-discriminator-not-set-78.patch
new file mode 100644
index 0000000..fd0dd62
--- /dev/null
+++ b/0001-Fix-seed-chunker-discriminator-not-set-78.patch
@@ -0,0 +1,96 @@
+From a1ec5a369d2e2a98c21e8f508f444a80f1aef496 Mon Sep 17 00:00:00 2001
+From: Saki <shadowofs@gmail.com>
+Date: Fri, 1 Sep 2017 00:38:06 +0800
+Subject: [PATCH] Fix seed chunker discriminator not set (#78)
+
+When user set a chunk_size, chunker.discriminator should be re-caculated
+with new chunk_size. Elsewise, Local seed cache can't be used to extract
+remote server.
+---
+ src/caseed.c | 31 ++-----------------------------
+ src/caseed.h |  4 +---
+ src/casync.c | 10 +---------
+ 3 files changed, 4 insertions(+), 41 deletions(-)
+
+diff --git a/src/caseed.c b/src/caseed.c
+index 6923750..ccf333a 100644
+--- a/src/caseed.c
++++ b/src/caseed.c
+@@ -773,39 +773,12 @@ int ca_seed_set_feature_flags(CaSeed *s, uint64_t flags) {
+         return ca_feature_flags_normalize(flags, &s->feature_flags);
+ }
+ 
+-int ca_seed_set_chunk_size_min(CaSeed *s, size_t cmin) {
++int ca_seed_set_chunk_size(CaSeed *s, size_t cmin, size_t cavg, size_t cmax) {
+         if (!s)
+                 return -EINVAL;
+-        if (cmin < CA_CHUNK_SIZE_LIMIT_MIN)
+-                return -EINVAL;
+-        if (cmin > CA_CHUNK_SIZE_LIMIT_MAX)
+-                return -EINVAL;
+-
+-        s->chunker.chunk_size_min = cmin;
+-        return 0;
+-}
+ 
+-int ca_seed_set_chunk_size_avg(CaSeed *s, size_t cavg) {
+-        if (!s)
+-                return -EINVAL;
+-        if (cavg < CA_CHUNK_SIZE_LIMIT_MIN)
+-                return -EINVAL;
+-        if (cavg > CA_CHUNK_SIZE_LIMIT_MAX)
+-                return -EINVAL;
+-
+-        s->chunker.chunk_size_avg = cavg;
+-        return 0;
+-}
+-
+-int ca_seed_set_chunk_size_max(CaSeed *s, size_t cmax) {
+-        if (!s)
+-                return -EINVAL;
+-        if (cmax < CA_CHUNK_SIZE_LIMIT_MIN)
+-                return -EINVAL;
+-        if (cmax > CA_CHUNK_SIZE_LIMIT_MAX)
+-                return -EINVAL;
++        ca_chunker_set_size(&s->chunker, cmin, cavg, cmax);
+ 
+-        s->chunker.chunk_size_max = cmax;
+         return 0;
+ }
+ 
+diff --git a/src/caseed.h b/src/caseed.h
+index f2d9f8e..55c3d43 100644
+--- a/src/caseed.h
++++ b/src/caseed.h
+@@ -36,9 +36,7 @@ int ca_seed_current_mode(CaSeed *seed, mode_t *ret);
+ 
+ int ca_seed_set_feature_flags(CaSeed *s, uint64_t flags);
+ 
+-int ca_seed_set_chunk_size_min(CaSeed *s, size_t cmin);
+-int ca_seed_set_chunk_size_avg(CaSeed *s, size_t cavg);
+-int ca_seed_set_chunk_size_max(CaSeed *s, size_t cmax);
++int ca_seed_set_chunk_size(CaSeed *s, size_t cmin, size_t cavg, size_t cmax);
+ 
+ int ca_seed_set_hardlink(CaSeed *s, bool b);
+ int ca_seed_set_chunks(CaSeed *s, bool b);
+diff --git a/src/casync.c b/src/casync.c
+index 346d08b..a74b0d9 100644
+--- a/src/casync.c
++++ b/src/casync.c
+@@ -2473,15 +2473,7 @@ static int ca_sync_propagate_flags_to_seeds(CaSync *s, uint64_t flags, size_t cm
+                 if (r < 0)
+                         return r;
+ 
+-                r = ca_seed_set_chunk_size_min(s->seeds[i], cmin);
+-                if (r < 0)
+-                        return r;
+-
+-                r = ca_seed_set_chunk_size_avg(s->seeds[i], cavg);
+-                if (r < 0)
+-                        return r;
+-
+-                r = ca_seed_set_chunk_size_max(s->seeds[i], cmax);
++                r = ca_seed_set_chunk_size(s->seeds[i], cmin, cavg, cmax);
+                 if (r < 0)
+                         return r;
+         }
diff --git a/casync.spec b/casync.spec
index 6293ed7..36e21af 100644
--- a/casync.spec
+++ b/casync.spec
@@ -3,7 +3,7 @@
 
 Name:           casync
 Version:        2
-Release:        3%{?gitcommit:.git%{gitcommitshort}}%{?dist}
+Release:        4%{?gitcommit:.git%{gitcommitshort}}%{?dist}
 Summary:        Content Addressable Data Synchronizer
 
 License:        LGPLv2+
@@ -14,6 +14,7 @@ Source0:        https://github.com/keszybz/casync/archive/%{?gitcommit}/casync-%
 Source0:        https://github.com/systemd/casync/archive/v%{version}/%{name}-%{version}.tar.gz
 %endif
 Patch0001:      0001-Fix-segv-in-ca_remote_forget_chunk.patch
+Patch0002:      0001-Fix-seed-chunker-discriminator-not-set-78.patch
 
 BuildRequires:  meson
 BuildRequires:  gcc
@@ -73,6 +74,9 @@ export LC_CTYPE=C.utf8
 %_udevrulesdir/75-casync.rules
 
 %changelog
+* Fri Sep 01 2017 Igor Gnatenko <ignatenkobrain@fedoraproject.org> - 2-4
+- Backport fix for setting chunk-size
+
 * Wed Aug 02 2017 Fedora Release Engineering <releng@fedoraproject.org> - 2-3
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_27_Binutils_Mass_Rebuild