diff --git a/ext/java/org/msgpack/jruby/Factory.java b/ext/java/org/msgpack/jruby/Factory.java
index dac2666d..34a6c22a 100644
--- a/ext/java/org/msgpack/jruby/Factory.java
+++ b/ext/java/org/msgpack/jruby/Factory.java
@@ -111,8 +111,8 @@ public IRubyObject registerTypeInternal(ThreadContext ctx, IRubyObject type, IRu
 
     extensionRegistry.put(extModule, (int) typeId, recursive, packerProc, unpackerProc);
 
-    if (extModule == runtime.getSymbol() && !packerProc.isNil()) {
-      hasSymbolExtType = true;
+    if (extModule == runtime.getSymbol()) {
+      hasSymbolExtType = !packerProc.isNil();
     }
 
     if (options != null) {
@@ -123,6 +123,8 @@ public IRubyObject registerTypeInternal(ThreadContext ctx, IRubyObject type, IRu
         } else {
           throw runtime.newArgumentError("oversized_integer_extension: true is only for Integer class");
         }
+      } else if (extModule == runtime.getModule("Integer")) {
+        hasBigIntExtType = false;
       }
     }
 
diff --git a/ext/msgpack/factory_class.c b/ext/msgpack/factory_class.c
index c4683a2a..8033ac7b 100644
--- a/ext/msgpack/factory_class.c
+++ b/ext/msgpack/factory_class.c
@@ -234,12 +234,12 @@ static VALUE Factory_register_type_internal(VALUE self, VALUE rb_ext_type, VALUE
 
     if(ext_module == rb_cSymbol) {
         fc->symbol_ext_type = ext_type;
-        if(NIL_P(options) || RTEST(rb_hash_aref(options, ID2SYM(rb_intern("packer"))))) {
-            fc->has_symbol_ext_type = true;
-        }
-        if(RTEST(options) && RTEST(rb_hash_aref(options, ID2SYM(rb_intern("optimized_symbols_parsing"))))) {
-            fc->optimized_symbol_ext_type = true;
-        }
+        fc->has_symbol_ext_type = NIL_P(options) || RTEST(packer_proc);
+        fc->optimized_symbol_ext_type = RTEST(options) && RTEST(rb_hash_aref(options, ID2SYM(rb_intern("optimized_symbols_parsing"))));
+    }
+
+    if(ext_module == rb_cInteger) {
+        fc->has_bigint_ext_type = false;
     }
 
     if(RTEST(options)) {
@@ -250,7 +250,6 @@ static VALUE Factory_register_type_internal(VALUE self, VALUE rb_ext_type, VALUE
                 rb_raise(rb_eArgError, "oversized_integer_extension: true is only for Integer class");
             }
         }
-
         if(RTEST(rb_hash_aref(options, ID2SYM(rb_intern("recursive"))))) {
             flags |= MSGPACK_EXT_RECURSIVE;
         }
diff --git a/lib/msgpack/factory.rb b/lib/msgpack/factory.rb
index dfe0201c..7803ee64 100644
--- a/lib/msgpack/factory.rb
+++ b/lib/msgpack/factory.rb
@@ -14,10 +14,12 @@ def register_type(type, klass, options = { packer: :to_msgpack_ext, unpacker: :f
           options[:packer] = packer.to_sym.to_proc
         when Method
           options[:packer] = packer.to_proc
-        when packer.respond_to?(:call)
-          options[:packer] = packer.method(:call).to_proc
         else
-          raise ::TypeError, "expected :packer argument to be a callable object, got: #{packer.inspect}"
+          if packer.respond_to?(:call)
+            options[:packer] = packer.method(:call).to_proc
+          else
+            raise ::TypeError, "expected :packer argument to be a callable object, got: #{packer.inspect}"
+          end
         end
 
         case unpacker = options[:unpacker]
@@ -27,10 +29,12 @@ def register_type(type, klass, options = { packer: :to_msgpack_ext, unpacker: :f
           options[:unpacker] = klass.method(unpacker).to_proc
         when Method
           options[:unpacker] = unpacker.to_proc
-        when packer.respond_to?(:call)
-          options[:unpacker] = unpacker.method(:call).to_proc
         else
-          raise ::TypeError, "expected :unpacker argument to be a callable object, got: #{unpacker.inspect}"
+          if unpacker.respond_to?(:call)
+            options[:unpacker] = unpacker.method(:call).to_proc
+          else
+            raise ::TypeError, "expected :unpacker argument to be a callable object, got: #{unpacker.inspect}"
+          end
         end
       end
 
@@ -51,7 +55,7 @@ def registered_types(selector=:both)
           type = ary[0]
           packer_proc = ary[1]
           unpacker_proc = nil
-          if unpacker.has_key?(type)
+          if unpacker.has_key?(type) && unpacker[type][0] == klass
             unpacker_proc = unpacker.delete(type)[1]
           end
           list << {type: type, class: klass, packer: packer_proc, unpacker: unpacker_proc}
@@ -85,7 +89,7 @@ def registered_types(selector=:both)
 
     def type_registered?(klass_or_type, selector=:both)
       case klass_or_type
-      when Class
+      when Module
         klass = klass_or_type
         registered_types(selector).any?{|entry| klass <= entry[:class] }
       when Integer
diff --git a/lib/msgpack/packer.rb b/lib/msgpack/packer.rb
index c05c7892..a42d7879 100644
--- a/lib/msgpack/packer.rb
+++ b/lib/msgpack/packer.rb
@@ -23,7 +23,7 @@ def registered_types
 
     def type_registered?(klass_or_type)
       case klass_or_type
-      when Class
+      when Module
         klass = klass_or_type
         registered_types.any?{|entry| klass <= entry[:class] }
       when Integer
diff --git a/lib/msgpack/unpacker.rb b/lib/msgpack/unpacker.rb
index e8bd7153..8cfaf44c 100644
--- a/lib/msgpack/unpacker.rb
+++ b/lib/msgpack/unpacker.rb
@@ -27,7 +27,7 @@ def registered_types
 
     def type_registered?(klass_or_type)
       case klass_or_type
-      when Class
+      when Module
         klass = klass_or_type
         registered_types.any?{|entry| klass == entry[:class] }
       when Integer