diff --git a/macrovision.js b/macrovision.js
index 4a368f1d..09628a3f 100644
--- a/macrovision.js
+++ b/macrovision.js
@@ -243,7 +243,7 @@ math.createUnit("nanoacres", {
     prefixes: "long"
 })
 math.createUnit("barnMegaparsecs", {
-    definition: "barn megaparsec",
+    definition: "1 barn megaparsec",
     prefixes: "long"
 })
 math.createUnit("firkins", {