diff --git a/usr.bin/units/units.lib b/usr.bin/units/units.lib
index 4d74e872d0b..6f56c301137 100644
--- a/usr.bin/units/units.lib
+++ b/usr.bin/units/units.lib
@@ -298,6 +298,7 @@ N			newton
 joule			nt-m
 J			joule
 cal			4.1868 joule
+ergon			erg
 
 / Electrical