diff --git a/t/bignum.t b/t/bignum.t
index 68776d9..883ebba 100644
--- a/t/bignum.t
+++ b/t/bignum.t
@@ -7,28 +7,30 @@ $INC{'Crypt/OpenSSL/Bignum.pm'}
   ? plan( tests    => 64 )
   : plan( skip_all => "Crypt::OpenSSL::Bignum required for bignum tests" );
 
+my @PARAM_NAMES = qw(n e d p q dmp1 dmq1 iqmp);
+
 sub check_datum {
-    my ( $p_expected, $p_actual ) = @_;
-    ok(
-        defined($p_expected)
-        ? $p_actual && $p_expected->equals($p_actual)
-        : !defined($p_actual)
-    );
+    my ( $p_expected, $p_actual, $name ) = @_;
+    if ( defined($p_expected) ) {
+        ok( $p_actual && $p_expected->equals($p_actual), $name );
+    }
+    else {
+        is( $p_actual, undef, $name );
+    }
 }
 
 sub check_key_parameters    # runs 8 tests
 {
-    my ( $p_rsa, $n, $e, $d, $p, $q, $dmp1, $dmq1, $iqmp ) = @_;
+    my ( $p_rsa, $label, $n, $e, $d, $p, $q, $dmp1, $dmq1, $iqmp ) = @_;
     my ( $rn, $re, $rd, $rp, $rq, $rdmp1, $rdmq1, $riqmp ) = $p_rsa->get_key_parameters();
 
-    check_datum( $n,    $rn );
-    check_datum( $e,    $re );
-    check_datum( $d,    $rd );
-    check_datum( $p,    $rp );
-    check_datum( $q,    $rq );
-    check_datum( $dmp1, $rdmp1 );
-    check_datum( $dmq1, $rdmq1 );
-    check_datum( $iqmp, $riqmp );
+    my @expected = ( $n, $e, $d, $p, $q, $dmp1, $dmq1, $iqmp );
+    my @actual   = ( $rn, $re, $rd, $rp, $rq, $rdmp1, $rdmq1, $riqmp );
+
+    for my $i ( 0 .. 7 ) {
+        check_datum( $expected[$i], $actual[$i],
+            "$label: $PARAM_NAMES[$i] matches expected" );
+    }
 }
 
 {
@@ -44,42 +46,42 @@ sub check_key_parameters    # runs 8 tests
     my $iqmp = $q->mod_inverse( $p, $ctx );
 
     my $rsa = Crypt::OpenSSL::RSA->new_key_from_parameters( $n, $e, $d, $p, $q );
-    ok($rsa);
+    ok( $rsa, "new_key_from_parameters(n,e,d,p,q) returns an object" );
 
     $rsa->use_no_padding();
 
     my $plaintext  = pack( 'C*', 100, 100, 100, 12 );
     my $ciphertext = Crypt::OpenSSL::Bignum->new_from_bin($plaintext)->mod_exp( $e, $n, $ctx )->to_bin();
-    check_key_parameters( $rsa, $n, $e, $d, $p, $q, $dmp1, $dmq1, $iqmp );
+    check_key_parameters( $rsa, "full key", $n, $e, $d, $p, $q, $dmp1, $dmq1, $iqmp );
 
-    ok( $rsa->encrypt($plaintext) eq $ciphertext );
-    ok( $rsa->decrypt($ciphertext) eq $plaintext );
+    is( $rsa->encrypt($plaintext), $ciphertext, "encrypt produces expected ciphertext" );
+    is( $rsa->decrypt($ciphertext), $plaintext, "decrypt recovers original plaintext" );
 
     my $rsa_pub = Crypt::OpenSSL::RSA->new_public_key( $rsa->get_public_key_string() );
 
     $rsa_pub->use_no_padding();
-    ok( $rsa->private_encrypt($ciphertext) eq $plaintext );
-    ok( $rsa_pub->public_decrypt($plaintext) eq $ciphertext );
+    is( $rsa->private_encrypt($ciphertext), $plaintext, "private_encrypt produces expected plaintext" );
+    is( $rsa_pub->public_decrypt($plaintext), $ciphertext, "public_decrypt produces expected ciphertext" );
 
     my @pub_parameters = $rsa_pub->get_key_parameters();
-    ok( scalar(@pub_parameters) == 8 );
+    is( scalar(@pub_parameters), 8, "public key returns 8 parameters" );
 
-    check_key_parameters( $rsa_pub, $n, $e );
+    check_key_parameters( $rsa_pub, "public key", $n, $e );
 
     $rsa = Crypt::OpenSSL::RSA->new_key_from_parameters( $n, $e, $d, $p );
-    check_key_parameters( $rsa, $n, $e, $d, $p, $q, $dmp1, $dmq1, $iqmp );
+    check_key_parameters( $rsa, "from (n,e,d,p)", $n, $e, $d, $p, $q, $dmp1, $dmq1, $iqmp );
 
     $rsa = Crypt::OpenSSL::RSA->new_key_from_parameters( $n, $e, $d, undef, $q );
-    check_key_parameters( $rsa, $n, $e, $d, $p, $q, $dmp1, $dmq1, $iqmp );
+    check_key_parameters( $rsa, "from (n,e,d,undef,q)", $n, $e, $d, $p, $q, $dmp1, $dmq1, $iqmp );
 
     $rsa = Crypt::OpenSSL::RSA->new_key_from_parameters( $n, $e );
-    check_key_parameters( $rsa, $n, $e );
+    check_key_parameters( $rsa, "from (n,e)", $n, $e );
 
     $rsa = Crypt::OpenSSL::RSA->new_key_from_parameters( $n, $e, $d );
-    check_key_parameters( $rsa, $n, $e, $d );
+    check_key_parameters( $rsa, "from (n,e,d)", $n, $e, $d );
 
     $rsa = Crypt::OpenSSL::RSA->new_key_from_parameters( $n, $e, undef, $p );
-    check_key_parameters( $rsa, $n, $e, $d, $p, $q, $dmp1, $dmq1, $iqmp );
+    check_key_parameters( $rsa, "from (n,e,undef,p)", $n, $e, $d, $p, $q, $dmp1, $dmq1, $iqmp );
 
     eval {
         Crypt::OpenSSL::RSA->new_key_from_parameters(
@@ -87,7 +89,7 @@ sub check_key_parameters    # runs 8 tests
             $e, $d, undef, $q
         );
     };
-    ok( $@ =~ /OpenSSL error: p not prime/ );
+    like( $@, qr/OpenSSL error: p not prime/, "bad n with q triggers 'p not prime' error" );
 
     #try again, to make sure the error queue was properly flushed
     eval {
@@ -96,5 +98,5 @@ sub check_key_parameters    # runs 8 tests
             $e, $d, undef, $q
         );
     };
-    ok( $@ =~ /OpenSSL error: p not prime/ );
+    like( $@, qr/OpenSSL error: p not prime/, "error queue flushed: repeat triggers same error" );
 }