diff --git a/t/core.t b/t/core.t
index 931b984c1..337320abe 100644
--- a/t/core.t
+++ b/t/core.t
@@ -1,6 +1,7 @@
 use strict;
 use warnings;
 use Test::More;
+use Test::Exception;
 use PDL::LiteF;
 use Config;
 use PDL::Types;
@@ -144,6 +145,22 @@ ok all(tapprox((5*sequence(5))->maximum_n_ind(3), pdl(4,3,2))), 'named dim';
 # pptest for dim with fixed value
 ok all(tapprox(crossp([1..3],[4..6]), pdl(-3,6,-3))), 'named dim=3';
 
+subtest 'dim compatibility' => sub {
+  for (
+    [\&append, [pdl(1), pdl(2), zeroes(1)], 2, qr/dim has size 1/, 'output => [1]; required [2]. output too small'],
+    [\&append, [pdl(1), pdl(2), zeroes(3,1)], 2, qr/dim has size 3/, 'output => [3,1]; required [2]. output too small'],
+    [\&append, [pdl(1), pdl(2), null], 2, [ 1, 2 ], 'output => null; required [2]'],
+  ) {
+    my ($func, $args, $exp_index, $exp, $label) = @$_;
+    if (ref $exp eq 'Regexp') {
+      throws_ok { $func->( @$args ) } $exp, $label;
+    } else {
+      $func->( @$args );
+      is_deeply( $args->[$exp_index]->unpdl, $exp, $label );
+    }
+  }
+};
+
 # test topdl
 
 { package # hide from PAUSE
diff --git a/t/primitive-append.t b/t/primitive-append.t
index 42c351022..f49a31708 100644
--- a/t/primitive-append.t
+++ b/t/primitive-append.t
@@ -1,7 +1,6 @@
 use strict;
 use warnings;
 use Test::More;
-use Test::Exception;
 use PDL::LiteF;
 
 is_deeply(
@@ -24,28 +23,6 @@ subtest 'append(null, null, $output)' => sub {
     is_deeply( $output->unpdl, [0], q{user's ndarray is unchanged} );
 };
 
-subtest 'output ndarray has different shape' => sub {
-
-    subtest 'output => [1]; required [2].  output too small' => sub {
-      my $output = zeroes(1);
-      throws_ok { append( pdl(1), pdl(2), $output ) }
-             qr/dim has size 1/;
-    };
-
-    subtest 'output => [3,1]; required [2]' => sub {
-        my $output = zeroes(3,1);
-        throws_ok { append( pdl(1), pdl(2), $output ) }
-               qr/dim has size 3/;
-    };
-
-    subtest 'output => null; required [2]' => sub {
-        my $output = null;
-        append( pdl(1), pdl(2), $output );
-        is_deeply( $output->unpdl, [ 1, 2 ], q{full append } );
-    };
-
-};
-
 subtest types => sub {
 
     is( append( zeroes( float, 2, 0 ), zeroes( 3, 0 ) )->type,