diff --git a/.github/scripts/publish-crate-if-needed.sh b/.github/scripts/publish-crate-if-needed.sh
index 48048a3..73473ce 100755
--- a/.github/scripts/publish-crate-if-needed.sh
+++ b/.github/scripts/publish-crate-if-needed.sh
@@ -19,6 +19,7 @@ trap 'rm -f "$response_file"' EXIT
 
 status="$(
   curl --silent --show-error \
+    --user-agent "srcmap-release (https://github.com/fallow-rs/srcmap)" \
     --output "$response_file" \
     --write-out '%{http_code}' \
     "https://crates.io/api/v1/crates/${crate_name}/${version}"
diff --git a/.github/scripts/publish-crate-if-needed.test.mjs b/.github/scripts/publish-crate-if-needed.test.mjs
index 7112d49..6f57b33 100644
--- a/.github/scripts/publish-crate-if-needed.test.mjs
+++ b/.github/scripts/publish-crate-if-needed.test.mjs
@@ -115,6 +115,12 @@ describe("publish-crate-if-needed", () => {
     assert.match(result.commands, /cargo publish -p srcmap-codec --no-verify/);
   });
 
+  it("sends a user agent, because crates.io refuses a lookup without one", async () => {
+    const result = await runPublishHelper();
+
+    assert.match(result.commands, /curl [^\n]*--user-agent /);
+  });
+
   it("stops when the crates.io lookup fails", async () => {
     const result = await runPublishHelper({ lookup: "failure" });