diff --git a/src/math/mathop.pysty b/src/math/mathop.pysty
index 741cb7a..2235c99 100644
--- a/src/math/mathop.pysty
+++ b/src/math/mathop.pysty
@@ -151,6 +151,7 @@ __END_OPTIONS_X__
 \DeclareCategory{AffVar}
 \DeclareCategory{Alg}
 \DeclareCategory{Field}
+\DeclareCategory{GrAb}
 
 %Set theory
 \DeclareSimpleMathOperator{card}