2 files changed, 2 insertions, 2 deletions
diff --git a/src/libstate/libstate.cpp b/src/libstate/libstate.cpp
index 3275c6493..20e736868 100644
--- a/src/libstate/libstate.cpp
+++ b/src/libstate/libstate.cpp
@@ -212,7 +212,7 @@ std::string Library_State::deref_alias(const std::string& key) const
 /*
 * Set/Add an option
 */
-void Library_State::set_option(const std::string key,
+void Library_State::set_option(const std::string& key,
                                const std::string& value)
    {
    set("conf", key, value);
diff --git a/src/libstate/libstate.h b/src/libstate/libstate.h
index 2493863a9..a0421953e 100644
--- a/src/libstate/libstate.h
+++ b/src/libstate/libstate.h
@@ -77,7 +77,7 @@ class BOTAN_DLL Library_State
       * @param key the key of the option to set
       * @param value the value to set
       */
-      void set_option(const std::string key, const std::string& value);
+      void set_option(const std::string& key, const std::string& value);
 
       /**
       * Add a parameter value to the "alias" section.