diff --git a/gap/quasigroups.gi b/gap/quasigroups.gi
index 04cbae9..f691a0a 100644
--- a/gap/quasigroups.gi
+++ b/gap/quasigroups.gi
@@ -842,7 +842,7 @@ InstallGlobalFunction( OppositeLoop, L -> IntoLoop( Opposite( L ) ) );
 ##  as can be preserved.
 
 InstallMethod( Opposite, "for magma",
-    [ IsMagma ],
+    [ IsMagma and HasMultiplicationTable],
     M -> ConstructorFromTable(M)( TransposedMat( MultiplicationTable( M ) ) )
 );