--- a/buffer.c
+++ b/buffer.c
@@ -935,13 +935,12 @@
 do_size( arg )
 	char *arg;
 {
-	char format[ 20 ];
-	int ret;
+	int ret = 0;
 
-	*format = '\0';
-	sscanf( arg, "%d%s", &ret, format );
+	char unit = '\0';
+	sscanf( arg, "%d%c", &ret, &unit );
 
-	switch( *format ){
+	switch( unit ){
 	case 'm':
 	case 'M':
 		ret = ret K K;
