minor warning fix
diff --git a/tinyxml2.cpp b/tinyxml2.cpp
index eda2200..9e92ae2 100644
--- a/tinyxml2.cpp
+++ b/tinyxml2.cpp
@@ -1576,7 +1576,7 @@
 				// Check for entities. If one is found, flush

 				// the stream up until the entity, write the 

 				// entity, and keep looking.

-				if ( flag[*q] ) {

+				if ( flag[(unsigned)(*q)] ) {

 					while ( p < q ) {

 						Print( "%c", *p );

 						++p;