diff --git a/release/c/README.md b/release/c/README.md
index 73f42f8..9b45a9c 100644
--- a/release/c/README.md
+++ b/release/c/README.md
@@ -21,3 +21,15 @@
 
 - It will not have long term support.
 - Newer versions make no promises about compatibility.
+
+
+# Mirror
+
+Wuffs' canonical repository is located at
+[github.com/google/wuffs](https://github.com/google/wuffs). If you just want to
+*use* Wuffs-the-library in its C form (instead of *modifying* its Wuffs form or
+otherwise needing Wuffs-the-language tools), a mirror of just the `release/c`
+directory is located at
+[github.com/google/wuffs-mirror-release-c](https://github.com/google/wuffs-mirror-release-c).
+By excluding everything else, the mirror is much smaller than and changes much
+less frequently than the canonical repository.
diff --git a/sync.txt b/sync.txt
index a09f434..587183a 100644
--- a/sync.txt
+++ b/sync.txt
@@ -1,6 +1,6 @@
-script/sync.sh ran on 2021-03-14
-Sibling directory (../wuffs) git revision is 3e5afc3e527041defb11bfe3746d57b87cc62d32
+script/sync.sh ran on 2021-04-01
+Sibling directory (../wuffs) git revision is 38d7548718abcf28adb27978d527c50b2e38dbd5
 Manifest (sha256sum values, filenames, versions):
-44756ef81a9bbe945c7667b3c76c6db44babd4db5692d93ca96b9b28a7d86fcb  release/c/README.md
+bb28889a02c5d89edf6544ded21495462d1f998f8ffa5d095f53ca5db29e2937  release/c/README.md
 3b6a0c78f663bb495d1972fbb2a87c717d70fbac5ea8cc1a50cb9afaa4b03f92  release/c/wuffs-v0.2.c
     #define WUFFS_VERSION_STRING "0.2.0+2078.20191219"