diff --git a/release b/release
index 26a915e..e37f571 100755
--- a/release
+++ b/release
@@ -1,13 +1,13 @@
 #!/bin/bash
-set -euo pipefail
+set -xeuo pipefail
 
 _err(){ >&2 echo "ERROR: $*"; exit 1; }
 
 git status --porcelain | grep -q "" &&
     _err "working tree is dirty, commit your changes first."
 
-[[ "$1" =~ ^v([0-9]+)\.([0-9]+)(\.([0-9]+))?$ ]] || \
-    _err "arg1 accepts the following formats: v1.0 v1.0.0"
+[[ "$1" =~ ^([0-9]+)\.([0-9]+)(\.([0-9]+))?$ ]] || \
+    _err "arg1 accepts the following formats: 1.0 1.0.0"
 
 git tag | grep -q "^$1$" &&
     _err "tag $1 already exists"
@@ -20,3 +20,11 @@ last_tag=$(git tag | tail -1)
     echo Changelog since "$last_tag":
     git log --pretty=format:"- [%cn] %s" "$last_tag"..HEAD
 } | git tag -u motiejus@jakstys.lt -F - "$1"
+
+shasum=$(git archive --prefix="bazel-zig-cc-$1/" --format=tar "$1" | \
+    gzip -n | sha256sum | cut -f1 -d" ")
+
+./relnotes.awk -v tag="$1" -v sha256sum="$shasum" README.md | sponge README.md
+
+git add README.md
+git commit -m "Update release notes for $1"
diff --git a/relnotes.awk b/relnotes.awk
new file mode 100755
index 0000000..3ac8a2f
--- /dev/null
+++ b/relnotes.awk
@@ -0,0 +1,34 @@
+#!/usr/bin/awk -f
+
+BEGIN {stage=0};
+
+!/```/ && stage==0 {
+    print
+}
+
+/```/ && stage==0 {
+    print "```"
+    print "BAZEL_ZIG_CC_VERSION = \""tag"\""
+    print ""
+    print "http_archive("
+    print "    name = \"bazel-zig-cc\","
+    print "    sha256 = \""sha256sum"\","
+    print "    strip_prefix = \"bazel-zig-cc-{}\".format(BAZEL_ZIG_CC_VERSION),"
+    print "    urls = [\"https://git.sr.ht/~motiejus/bazel-zig-cc/archive/{}.tar.gz\".format(BAZEL_ZIG_CC_VERSION)],"
+    print ")"
+    stage=1
+    next
+}
+
+!/^)$/ && stage==1 {
+    next
+};
+
+/^)$/ && stage==1 {
+    stage=2
+    next
+};
+
+stage==2 {
+    print;
+};