diff --git a/.ruby-version b/.ruby-version
index 37c2961..1effb00 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-2.7.2
+2.7
diff --git a/ext/mdbx_ext/database.c b/ext/mdbx_ext/database.c
index 1ebf17b..2bc2afa 100644
--- a/ext/mdbx_ext/database.c
+++ b/ext/mdbx_ext/database.c
@@ -135,11 +135,7 @@ rmdbx_key_for( VALUE key, MDBX_val *ckey )
 void
 rmdbx_val_for( VALUE self, VALUE val, MDBX_val *data )
 {
-	VALUE serialize_proc = rb_iv_get( self, "@serializer" );
-
-	if ( ! NIL_P( serialize_proc ) )
-		val = rb_funcall( serialize_proc, rb_intern("call"), 1, val );
-
+	val = rb_funcall( self, rb_intern("serialize"), 1, val );
 	Check_Type( val, T_STRING );
 
 	data->iov_len  = RSTRING_LEN( val );
@@ -148,20 +144,6 @@ rmdbx_val_for( VALUE self, VALUE val, MDBX_val *data )
 }
 
 
-/*
- * Deserialize and return a value.
- */
-VALUE
-rmdbx_deserialize( VALUE self, VALUE val )
-{
-	VALUE deserialize_proc = rb_iv_get( self, "@deserializer" );
-	if ( ! NIL_P( deserialize_proc ) )
-		val = rb_funcall( deserialize_proc, rb_intern("call"), 1, val );
-
-	return val;
-}
-
-
 /*
  * Open the DB environment handle.
  *
@@ -355,7 +337,7 @@ rmdbx_get_val( VALUE self, VALUE key )
 	switch ( rc ) {
 		case MDBX_SUCCESS:
 			rv = rb_str_new( data.iov_base, data.iov_len );
-			return rmdbx_deserialize( self, rv );
+			return rb_funcall( self, rb_intern("deserialize"), 1, rv );
 
 		case MDBX_NOTFOUND:
 			return Qnil;
@@ -439,13 +421,17 @@ rmdbx_set_subdb( VALUE self, VALUE name )
 	if ( db->txn )
 		rb_raise( rmdbx_eDatabaseError, "Unable to change collection: transaction open" );
 
-	xfree( db->subdb ); 
+	xfree( db->subdb );
 	db->subdb = NULL;
 
 	if ( ! NIL_P(name) ) {
 		size_t len = RSTRING_LEN( name ) + 1;
 		db->subdb = malloc( len );
 		strlcpy( db->subdb, StringValuePtr(name), len );
+		rmdbx_log_obj( self, "debug", "setting subdb: %s", RSTRING_PTR(name) );
+	}
+	else {
+		rmdbx_log_obj( self, "debug", "clearing subdb" );
 	}
 
 	/* Reset the db handle and issue a single transaction to reify
@@ -644,11 +630,11 @@ rmdbx_each_value_i( VALUE self )
 
 	if ( mdbx_cursor_get( db->cursor, &key, &data, MDBX_FIRST ) == MDBX_SUCCESS ) {
 		VALUE rv = rb_str_new( data.iov_base, data.iov_len );
-		rb_yield( rmdbx_deserialize( self, rv ) );
+		rb_yield( rb_funcall( self, rb_intern("deserialize"), 1, rv ) );
 
 		while ( mdbx_cursor_get( db->cursor, &key, &data, MDBX_NEXT ) == MDBX_SUCCESS ) {
 			rv = rb_str_new( data.iov_base, data.iov_len );
-			rb_yield( rmdbx_deserialize( self, rv ) );
+			rb_yield( rb_funcall( self, rb_intern("deserialize"), 1, rv ) );
 		}
 	}
 
@@ -694,12 +680,15 @@ rmdbx_each_pair_i( VALUE self )
 	if ( mdbx_cursor_get( db->cursor, &key, &data, MDBX_FIRST ) == MDBX_SUCCESS ) {
 		VALUE rkey = rb_str_new( key.iov_base, key.iov_len );
 		VALUE rval = rb_str_new( data.iov_base, data.iov_len );
-		rb_yield( rb_assoc_new( rkey, rmdbx_deserialize( self, rval ) ) );
+		rval = rb_funcall( self, rb_intern("deserialize"), 1, rval );
+		rb_yield( rb_assoc_new( rkey, rval  ) );
 
 		while ( mdbx_cursor_get( db->cursor, &key, &data, MDBX_NEXT ) == MDBX_SUCCESS ) {
 			rkey = rb_str_new( key.iov_base, key.iov_len );
 			rval = rb_str_new( data.iov_base, data.iov_len );
-			rb_yield( rb_assoc_new( rkey, rmdbx_deserialize( self, rval ) ) );
+			rval = rb_funcall( self, rb_intern("deserialize"), 1, rval );
+
+			rb_yield( rb_assoc_new( rkey, rval ) );
 		}
 	}
 
diff --git a/lib/mdbx/database.rb b/lib/mdbx/database.rb
index 4f53dfc..43ae417 100644
--- a/lib/mdbx/database.rb
+++ b/lib/mdbx/database.rb
@@ -364,6 +364,34 @@ class MDBX::Database
 	protected
 	#########
 
+
+	### Safely serialize a value, closing any open transaction and re-raising
+	### if necessary.
+	###
+	def serialize( val )
+		return val unless self.serializer
+		return self.serializer.call( val )
+
+	rescue => err
+		self.close_transaction( false )
+		raise err
+	end
+
+
+	### Safely deserialize a value, closing any open transaction and re-raising
+	### if necessary.
+	###
+	def deserialize( val )
+		return val unless self.deserializer
+		return self.deserializer.call( val )
+
+	rescue => err
+		self.close_transaction( false )
+		raise err
+	end
+
+
+
 	### Yield and return the block, opening a snapshot first if
 	### there isn't already a transaction in progress.  Closes
 	### the snapshot if this method opened it.
diff --git a/spec/mdbx/database_spec.rb b/spec/mdbx/database_spec.rb
index e10fe0e..e228937 100644
--- a/spec/mdbx/database_spec.rb
+++ b/spec/mdbx/database_spec.rb
@@ -265,12 +265,22 @@ RSpec.describe( MDBX::Database ) do
 
 		it "reverts back to previous collection if the block raises an exception" do
 			expect( db.collection ).to be_nil
-			begin
+			expect {
 				db.collection( 'bucket1' ) do
 					db.collection( 'bucket2' ) { raise "ka-bloooey!" }
 				end
-			rescue
-			end
+			}.to raise_error( RuntimeError, /ka-bloooey!/ )
+			expect( db.collection ).to be_nil
+		end
+
+		it "reverts back to previous collection if serialization fails" do
+            db.serializer = ->( v ) { raise "ka-bloooey!" }
+			expect( db.collection ).to be_nil
+			expect {
+				db.collection( 'bucket1' ) do
+					db.collection( 'bucket2' ) {|sdb| sdb['foo'] = 1 }
+				end
+			}.to raise_error( RuntimeError, /ka-bloooey!/ )
 			expect( db.collection ).to be_nil
 		end