diff --git a/ext/mdbx_ext/database.c b/ext/mdbx_ext/database.c
index 35753c7..cbf1739 100644
--- a/ext/mdbx_ext/database.c
+++ b/ext/mdbx_ext/database.c
@@ -603,7 +603,13 @@ rmdbx_set_subdb( int argc, VALUE *argv, VALUE self )
 		strcpy( prev_db, db->subdb );
 	}
 
-	db->subdb = NIL_P( subdb ) ? NULL : StringValueCStr( subdb );
+	if ( NIL_P(subdb) ) {
+		db->subdb = NULL;
+	}
+	else {
+		subdb = rb_funcall( subdb, rb_intern("to_s"), 0 );
+		db->subdb = StringValueCStr( subdb );
+	}
 	rmdbx_close_dbi( db );
 
 	/*
diff --git a/spec/mdbx/database_spec.rb b/spec/mdbx/database_spec.rb
index 0b62512..ff1f8e7 100644
--- a/spec/mdbx/database_spec.rb
+++ b/spec/mdbx/database_spec.rb
@@ -224,6 +224,11 @@ RSpec.describe( MDBX::Database ) do
 			expect( db['key'] ).to be_truthy
 		end
 
+		it "automatically stringifies the collection argument" do
+			db.collection( :bucket )
+			expect( db.collection ).to eq( 'bucket' )
+		end
+
 		it "revert back to the previous collection when used in a block" do
 			expect( db.collection ).to be_nil
 			db.collection( 'bucket' ) { 'no-op' }