diff --git a/tools/bsp2img/bsp2img.c b/tools/bsp2img/bsp2img.c
index e3e901464..3c11c2397 100644
--- a/tools/bsp2img/bsp2img.c
+++ b/tools/bsp2img/bsp2img.c
@@ -904,7 +904,7 @@ main (int argc, char *argv[])
 
 	/* Write image */
 
-	outfile = Qopen (options.outf_name, "w");
+	outfile = Qopen (options.outf_name, "wb");
 	if (outfile == NULL) {
 		fprintf (stderr, "Error opening output file %s.\n", options.outf_name);