diff --git a/src/security/sec-rule.hpp b/src/security/sec-rule.hpp
index 6a005be..43f504c 100644
--- a/src/security/sec-rule.hpp
+++ b/src/security/sec-rule.hpp
@@ -42,6 +42,7 @@
     }
   };
 
+  explicit
   SecRule(bool isPositive)
     : m_isPositive(isPositive)
   {