diff --git a/crates/relay/src/site.rs b/crates/relay/src/site.rs
index f5ee35df29fcc5400350364ae505880d7a36c8b4..11a7a96bd515c5c8b6c845fa845090bbb49125b1 100644
--- a/crates/relay/src/site.rs
+++ b/crates/relay/src/site.rs
@@ -173,6 +173,9 @@ fn keep_crash(
     else {
         return "411 Length Required";
     };
+    if length == 0 {
+        return "400 Bad Request";
+    }
     if length > REPORT {
         return "413 Content Too Large";
     }
diff --git a/crates/relay/tests/site.rs b/crates/relay/tests/site.rs
index f272d101467b3522634d4becf4a86e6e82f9064c..44638b2d2eb3186e815394f435cee833fa9b88dd 100644
--- a/crates/relay/tests/site.rs
+++ b/crates/relay/tests/site.rs
@@ -170,6 +170,9 @@ fn crash_reports_are_kept_small_and_few_and_never_echoed() {
         b"POST /crash HTTP/1.1\r\nContent-Type: text/plain\r\nContent-Length: 2\r\n\r\n\xff\xfe",
     );
     assert!(invalid.starts_with("HTTP/1.1 400"), "{invalid}");
+    let empty =
+        site.send(b"POST /crash HTTP/1.1\r\nContent-Type: text/plain\r\nContent-Length: 0\r\n\r\n");
+    assert!(empty.starts_with("HTTP/1.1 400"), "{empty}");
 
     // One sender is held to a few an hour; another, by the proxy's word, still gets in.
     let sent = (0..relay::site::PER_ADDRESS)