diff --git a/src/tools/compiletest/src/command-list.rs b/src/tools/compiletest/src/command-list.rs
index b34c276ab19..8349c3085cc 100644
--- a/src/tools/compiletest/src/command-list.rs
+++ b/src/tools/compiletest/src/command-list.rs
@@ -208,6 +208,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "pretty-compare-only",
     "pretty-expanded",
     "pretty-mode",
+    "reference",
     "regex-error-pattern",
     "remap-src-base",
     "revisions",