diff --git a/openbr/openbr_plugin.h b/openbr/openbr_plugin.h
index 981f360..759b360 100644
--- a/openbr/openbr_plugin.h
+++ b/openbr/openbr_plugin.h
@@ -1206,7 +1206,7 @@ public:
     static QSharedPointer<Distance> fromAlgorithm(const QString &algorithm); /*!< \brief Retrieve an algorithm's distance. */
     virtual void train(const TemplateList &src) { (void) src; } /*!< \brief Train the distance. */
     virtual void compare(const TemplateList &target, const TemplateList &query, Output *output) const; /*!< \brief Compare two template lists. */
-    QList<float> compare(const TemplateList &targets, const Template &query) const; /*!< \brief Compute the normalized distance between a template and a template list. */
+    virtual QList<float> compare(const TemplateList &targets, const Template &query) const; /*!< \brief Compute the normalized distance between a template and a template list. */
     virtual float compare(const Template &a, const Template &b) const = 0; /*!< \brief Compute the distance between two templates. */
 
 protected: