diff --git a/include/nana/gui/msgbox.hpp b/include/nana/gui/msgbox.hpp
index f8032094..3b035e58 100644
--- a/include/nana/gui/msgbox.hpp
+++ b/include/nana/gui/msgbox.hpp
@@ -267,7 +267,7 @@ namespace nana
 
             If not called, the default is 100 pixels
         */
-		void min_width_entry_field( int pixels );
+		void min_width_entry_field( unsigned pixels );
 
 	private:
 		void _m_fetch_args(std::vector<abstract_content*>&);
diff --git a/source/gui/msgbox.cpp b/source/gui/msgbox.cpp
index b7cc392c..75ce6a23 100644
--- a/source/gui/msgbox.cpp
+++ b/source/gui/msgbox.cpp
@@ -1285,7 +1285,7 @@ namespace nana
 
 	//Inputbox set minimum width entry field(https://github.com/cnjinhao/nana/pull/234)
 	//Contributed by James Bremner
-	void inputbox::min_width_entry_field( int pixels )
+	void inputbox::min_width_entry_field( unsigned pixels )
 	{
 	    // don't let the entry fields vanish entirely
 	    if( pixels < 10 )