diff --git a/lib/conformal.gi b/lib/conformal.gi
index ce265c4..75a146b 100644
--- a/lib/conformal.gi
+++ b/lib/conformal.gi
@@ -115,23 +115,30 @@ InstallMethod( ConformalSymplecticGroupCons,
     "IsField and IsFinite",
     "IsBilinearForm" ],
   function( filt, d, F, form )
-  local g, stored, wanted, mat1, mat2, mat, matinv, gens, gg;
+  local g, stored, matrix_filt, form_matrix, wanted, mat1, mat2, mat, matinv,
+        gens, gg;
 
   # Create the default generators and form.
   g:= ConformalSymplecticGroupCons( filt, d, F );
   stored:= InvariantBilinearFormUpToScalars( g ).matrix;
+  matrix_filt:= ConstructingFilter( stored );
+  Assert( 1, ForAll( GeneratorsOfGroup( g ),
+                     x -> ConstructingFilter( x ) = matrix_filt ) );
 
   # If the prescribed form fits then just return.
-  if stored = form!.matrix then
+  # We do not require that 'form!.matrix' is in 'matrix_filt',
+  # only its entries describe the desired form.
+  form_matrix:= Matrix( matrix_filt, F, form!.matrix );
+  if stored = form_matrix then
     return g;
   fi;
 
   # Compute a base change matrix.
   # (Check that the canonical forms are equal.)
   wanted:= BilinearFormByMatrix( stored, F );
-  mat1:= BaseChangeToCanonical( form );
-  mat2:= BaseChangeToCanonical( wanted );
-  if mat1 * form!.matrix * TransposedMat( mat1 ) <>
+  mat1:= Matrix( matrix_filt, F, BaseChangeToCanonical( form ) );
+  mat2:= Matrix( matrix_filt, F, BaseChangeToCanonical( wanted ) );
+  if mat1 * form_matrix * TransposedMat( mat1 ) <>
      mat2 * stored * TransposedMat( mat2 ) then
     Error( "canonical forms of <form> and <wanted> differ" );
   fi;
@@ -139,8 +146,7 @@ InstallMethod( ConformalSymplecticGroupCons,
   matinv:= mat^-1;
 
   # Create the group w.r.t. the prescribed form.
-  gens:= List( GeneratorsOfGroup( g ),
-               x -> Matrix( matinv * x * mat, stored ) );
+  gens:= List( GeneratorsOfGroup( g ), x -> matinv * x * mat );
   gg:= GroupWithGenerators( gens );
 
   UseIsomorphismRelation( g, gg );
@@ -150,7 +156,7 @@ InstallMethod( ConformalSymplecticGroupCons,
   fi;
 
   SetInvariantBilinearFormUpToScalars( gg,
-    rec( matrix:= Matrix( form!.matrix, stored ), baseDomain:= F ) );
+    rec( matrix:= form_matrix, baseDomain:= F ) );
 
   if HasIsFullSubgroupGLRespectingBilinearFormUpToScalars( g ) then
     SetIsFullSubgroupGLRespectingBilinearFormUpToScalars( gg,
diff --git a/tst/adv/conformal.tst b/tst/adv/conformal.tst
index 859c2d2..5a485be 100644
--- a/tst/adv/conformal.tst
+++ b/tst/adv/conformal.tst
@@ -1,18 +1,18 @@
-#@local is_equal, q, F, d, filt, g, stored, pi, permmat, form, gg, pg, sp
+#@local q, F, d, filts, filt, g, stored, pi, permmat, form, gg, pg, sp
 
 gap> START_TEST( "Forms: conformal.tst" );
 
-# Provide an auxiliary function (until GAP's '=' gets fast).
-gap> is_equal:= function( G1, G2 )
->      return IsSubset( G1, GeneratorsOfGroup( G2 ) ) and
->             IsSubset( G2, GeneratorsOfGroup( G1 ) );
->    end;;
-
 # Test the creation of conformal symplectic groups.
 gap> for q in [ 2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 19, 23, 25 ] do
 >      F:= GF(q);
 >      for d in [ 2, 4 .. 8 ] do
->        for filt in [ IsPlistRep, IsPlistMatrixRep ] do
+>        filts:= [ IsPlistRep, IsPlistMatrixRep ];
+>        if q = 2 then
+>          Add( filts, IsGF2MatrixRep );
+>        elif q <= 256 then
+>          Add( filts, Is8BitMatrixRep );
+>        fi;
+>        for filt in filts do
 >          PushOptions( rec( ConstructingFilter:= filt ) );
 > 
 >          g:= ConformalSymplecticGroup( d, F );
@@ -30,24 +30,23 @@ gap> for q in [ 2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 19, 23, 25 ] do
 >          if filt <> IsPlistRep and not filt( One( gg ) ) then
 >            Error( "wrong repres. of matrices" );
 >          fi;
->          if not ( is_equal( g, ConformalSymplecticGroup( g ) ) and
->                   ( is_equal( g, ConformalSymplecticGroup( stored ) ) or
+>          if not ( g = ConformalSymplecticGroup( g ) and
+>                   ( g = ConformalSymplecticGroup( stored ) or
 >                     BaseDomain( stored ) <> F ) and
->                   is_equal( g, ConformalSymplecticGroup( d, q ) ) and
->                   is_equal( g, ConformalSymplecticGroup( form ) ) and
->                   is_equal( g, ConformalSymplecticGroup( d, q, g ) ) and
->                   is_equal( g, ConformalSymplecticGroup( d, q, stored ) ) and
->                   is_equal( g, ConformalSymplecticGroup( d, q, form ) ) and
->                   is_equal( g, ConformalSymplecticGroup( d, F, g ) ) and
->                   is_equal( g, ConformalSymplecticGroup( d, F, stored ) ) and
->                   is_equal( g, ConformalSymplecticGroup( d, F, form ) ) and
+>                   g = ConformalSymplecticGroup( d, q ) and
+>                   g = ConformalSymplecticGroup( form ) and
+>                   g = ConformalSymplecticGroup( d, q, g ) and
+>                   g = ConformalSymplecticGroup( d, q, stored ) and
+>                   g = ConformalSymplecticGroup( d, q, form ) and
+>                   g = ConformalSymplecticGroup( d, F, g ) and
+>                   g = ConformalSymplecticGroup( d, F, stored ) and
+>                   g = ConformalSymplecticGroup( d, F, form ) and
 >                   IsSubset( gg, GeneratorsOfGroup( gg ) ) and
 >                   IsSubset( g, List( GeneratorsOfGroup( gg ), x -> x^pi ) ) ) then
 >            Error( "problem with CSp(", d, ",", q, ")" );
 >          fi;
 > 
->          if Size( g ) < 10^7 and filt = IsPlistRep then
-> # Change this as soon as also `IsPlistMatrixRep` works!
+>          if Size( g ) < 10^7 then
 >            pg:= ConformalSymplecticGroup( IsPermGroup, d, q );
 >            if Size( g ) <> Size( pg ) then
 >              Error( "problem with CSp(IsPermGroup, ", d, ",", q, ")" );
@@ -59,8 +58,7 @@ gap> for q in [ 2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 19, 23, 25 ] do
 >            Error( "wrong repres. of matrices" );
 >          fi;
 >          g:= ConformalSymplecticGroup( sp );
->        # if not IsSubset( g, sp ) then   # make this fast in the GAP library
->          if ForAny( GeneratorsOfGroup( sp ), x -> not x in g ) then
+>          if not IsSubset( g, sp ) then
 >            Error( "problem with CSp(", d, ",", q, ")" );
 >          fi;
 >