diff --git a/src/main/java/org/jruby/ext/openssl/ASN1.java b/src/main/java/org/jruby/ext/openssl/ASN1.java
index 6a221049..0dd7e337 100644
--- a/src/main/java/org/jruby/ext/openssl/ASN1.java
+++ b/src/main/java/org/jruby/ext/openssl/ASN1.java
@@ -1506,7 +1506,7 @@ public Primitive(Ruby runtime, RubyClass type) {
         @Override
         @JRubyMethod
         public IRubyObject to_der(final ThreadContext context) {
-            if ( value(context).isNil() ) {
+            if ( value(context).isNil() && !isNull() ) {
                 // MRI compatibility but avoids Java exceptions as well e.g.
                 // Java::JavaLang::NumberFormatException
                 //    java.math.BigInteger.<init>(BigInteger.java:296)
@@ -1596,7 +1596,7 @@ boolean isExplicitTagging() {
 
         @Override
         boolean isImplicitTagging() {
-            IRubyObject tagging = getInstanceVariable("@tagging");
+            IRubyObject tagging = tagging();
             if ( tagging.isNil() ) return true;
             return "IMPLICIT".equals( tagging.toString() );
         }
@@ -1606,6 +1606,10 @@ boolean isEOC() {
             return false;
         }
 
+        private boolean isNull() {
+            return "Null".equals(getMetaClass().getRealClass().getBaseName());
+        }
+
         @Override
         byte[] toDER(final ThreadContext context) throws IOException {
             return toASN1(context).toASN1Primitive().getEncoded(ASN1Encoding.DER);
diff --git a/src/test/ruby/test_asn1.rb b/src/test/ruby/test_asn1.rb
index 0e97f190..9867a4b3 100644
--- a/src/test/ruby/test_asn1.rb
+++ b/src/test/ruby/test_asn1.rb
@@ -245,9 +245,7 @@ def test_encode_nested_set_to_der
   end
 
   def test_null
-    # TODO: Import Issue -- Is this related to the comment below in test_encode_all?
-    # TypeError: nil value
-    #encode_decode_test B(%w{ 05 00 }), OpenSSL::ASN1::Null.new(nil)
+    encode_decode_test B(%w{ 05 00 }), OpenSSL::ASN1::Null.new(nil)
     assert_raise(OpenSSL::ASN1::ASN1Error) {
       OpenSSL::ASN1.decode(B(%w{ 05 01 00 }))
     }
@@ -384,13 +382,11 @@ def test_simple_to_der
 
   def test_sequence
     encode_decode_test B(%w{ 30 00 }), OpenSSL::ASN1::Sequence.new([])
-    # TODO: Import Issue
-    # TypeError: nil value
-    #encode_decode_test B(%w{ 30 07 05 00 30 00 04 01 00 }), OpenSSL::ASN1::Sequence.new([
-    #  OpenSSL::ASN1::Null.new(nil),
-    #  OpenSSL::ASN1::Sequence.new([]),
-    #  OpenSSL::ASN1::OctetString.new(B(%w{ 00 }))
-    #])
+    encode_decode_test B(%w{ 30 07 05 00 30 00 04 01 00 }), OpenSSL::ASN1::Sequence.new([
+     OpenSSL::ASN1::Null.new(nil),
+     OpenSSL::ASN1::Sequence.new([]),
+     OpenSSL::ASN1::OctetString.new(B(%w{ 00 }))
+    ])
 
     expected = OpenSSL::ASN1::Sequence.new([OpenSSL::ASN1::OctetString.new(B(%w{ 00 }))])
     expected.indefinite_length = true