diff --git a/Libtmp/Simplex/t/simplex.t b/Libtmp/Simplex/t/simplex.t
index 16dd4a9a1..5e6da56c0 100644
--- a/Libtmp/Simplex/t/simplex.t
+++ b/Libtmp/Simplex/t/simplex.t
@@ -3,6 +3,7 @@ use warnings;
 use Test::More;
 use PDL::LiteF;
 use PDL::Opt::Simplex;
+use Test::PDL -atol => 1e-3;
 
 sub test_simplex {
   local $Test::Builder::Level = $Test::Builder::Level + 1;
@@ -15,24 +16,23 @@ sub test_simplex {
       sumover( ( $_[0] - $dis )**2 ) + 1;
     }, $nolog ? () : $logsub,
   );
-  ok all PDL::Core::approx($opt, $dis, 1e-3), 'optimum' or diag "got=$opt";
-  ok PDL::Core::approx($ssize, 0, 1e-3), 'ssize' or diag "got=$ssize";
-  ok PDL::Core::approx($optval, 1, 1e-3), 'optval' or diag "got=$optval";
+  is_pdl $opt, $dis, 'optimum' or diag "got=$opt";
+  is_pdl $ssize, pdl(0), 'ssize' or diag "got=$ssize";
+  is_pdl $optval, pdl(1), 'optval' or diag "got=$optval";
   ok $log_called, 'log called' if !$nolog;
   my @init_dims = $init->dims;
   my @exp_dims = ($init_dims[0], 1, @init_dims[2..$#init_dims]);
   is_deeply [$opt->dims], \@exp_dims, 'dims optimum right';
 }
 
-test_simplex(pdl(2,2), 0.01, pdl(0,1));
-test_simplex(pdl(2,2), pdl(0.01,0.01), pdl(0,1));
-test_simplex(pdl(2,2), pdl(0.01,0.01), pdl(0,1), 1);
-test_simplex(pdl(2,2,2), pdl(0.01,0.01,0.01), pdl(0,1,2));
-test_simplex(my $p = pdl(q[-1 -1; -1.1 -1; -1.1 -0.9]), pdl(0.01,0.01), pdl(0,1));
-test_simplex($p, undef, pdl(-1,1));
+test_simplex(pdl(2,2), 0.01, pdl([[0,1]]));
+test_simplex(pdl(2,2), pdl(0.01,0.01), pdl([[0,1]]));
+test_simplex(pdl(2,2), pdl(0.01,0.01), pdl([[0,1]]), 1);
+test_simplex(pdl(2,2,2), pdl(0.01,0.01,0.01), pdl([[0,1,2]]));
+test_simplex(my $p = pdl(q[-1 -1; -1.1 -1; -1.1 -0.9]), pdl(0.01,0.01), pdl([[0,1]]));
+test_simplex($p, undef, pdl([[-1,1]]));
 
 my $s = make_simplex(pdl(0,0,0), pdl(0.12,0.12,0.12));
-ok all approx $s, pdl '0 -0.06 -0.08; 0.12 -0.06 -0.08; 0 0.06 -0.08; 0 0 0.04'
-  or diag "got=$s";
+is_pdl $s, pdl '0 -0.06 -0.08; 0.12 -0.06 -0.08; 0 0.06 -0.08; 0 0 0.04';
 
 done_testing;
diff --git a/Libtmp/Slatec/t/linfit.t b/Libtmp/Slatec/t/linfit.t
index 356ea48e1..4b785577e 100644
--- a/Libtmp/Slatec/t/linfit.t
+++ b/Libtmp/Slatec/t/linfit.t
@@ -3,6 +3,7 @@ use warnings;
 use Test::More;
 use PDL::Fit::Linfit;
 use PDL::LiteF;
+use Test::PDL;
 
 {
 # Simple Test Case:
@@ -20,7 +21,7 @@ my ($yfit, $coeffs) = PDL::linfit1d($data, $fitFuncs);
 
 my @coefs = $coeffs->list;
 
-ok all approx( $coeffs, pdl([3,2,3]) );
+is_pdl $coeffs, pdl([3,2,3]);
 }
 
 {
@@ -92,7 +93,7 @@ my ($yfit, $coeffs) = linfit1d($data, $fitFuncs);
 
 my @coefs = $coeffs->list;
 
-ok all approx( $coeffs, pdl( \@expectedCoefs ) );
+is_pdl $coeffs, pdl( \@expectedCoefs );
 }
 
 done_testing;
diff --git a/Libtmp/Slatec/t/slatec-polyfit-weight.t b/Libtmp/Slatec/t/slatec-polyfit-weight.t
index cf8d792f5..0f22b0bab 100644
--- a/Libtmp/Slatec/t/slatec-polyfit-weight.t
+++ b/Libtmp/Slatec/t/slatec-polyfit-weight.t
@@ -3,6 +3,7 @@ use warnings;
 use Test::More;
 use Test::Exception;
 use PDL::LiteF;
+use Test::PDL;
 use PDL::Slatec;
 
 ## Issue information
@@ -25,13 +26,13 @@ lives_ok { $polyfit_orig = polyfit( $x, $y, $x->ones, 4, .0001 ); } 'polyfit() w
 subtest 'Passing the weight in a PDL of length 1' => sub {
 	my $polyfit_pdl_len_one;
 	lives_ok { $polyfit_pdl_len_one = polyfit( $x, $y, pdl(1), 4, .0001 ); };
-	ok( approx($polyfit_orig, $polyfit_pdl_len_one)->all, 'passing a PDL of length 1 expands to the correct length' );
+	is_pdl $polyfit_orig, $polyfit_pdl_len_one, 'passing a PDL of length 1 expands to the correct length';
 };
 
 subtest 'Passing the weight in a Perl scalar' => sub {
 	my $polyfit_perl_scalar;
 	lives_ok { $polyfit_perl_scalar = polyfit( $x, $y, 1, 4, .0001 ) };
-	ok( approx($polyfit_orig, $polyfit_perl_scalar)->all, 'passing a Perl scalar expands to the correct length' );
+	is_pdl $polyfit_orig, $polyfit_perl_scalar, 'passing a Perl scalar expands to the correct length';
 };
 
 done_testing;