diff --git a/sc2/src/libs/input/sdl/input.c b/sc2/src/libs/input/sdl/input.c
index fabecd3e1..83ced418f 100644
--- a/sc2/src/libs/input/sdl/input.c
+++ b/sc2/src/libs/input/sdl/input.c
@@ -470,6 +470,7 @@ ProcessInputEvent (const SDL_Event *Event)
 		while (Event->text.text[i])
 		{
 			UniChar map_key = Event->text.text[i++];
+			map_key &= 0xFF; /* Interpret as unsigned byte */
 
 			/* Decode any UTF-8 keys */
 			if (map_key >= 0xC0 && map_key < 0xE0)