diff --git a/groff/math.tmac b/groff/math.tmac
index ab099cd..3a5b8ad 100644
--- a/groff/math.tmac
+++ b/groff/math.tmac
@@ -80,7 +80,7 @@ define box 'special Bx'
 .\" Draws a straight line
 .\" for equation systems
 .EQ
-define matrixsep 'special Mx'
+define matrixeq 'special Mx'
 .EN
 .de Mx
 .  ds 0s \