diff --git a/support/tock_support_cif.h b/support/tock_support_cif.h
index aa96449..87fb06c 100644
--- a/support/tock_support_cif.h
+++ b/support/tock_support_cif.h
@@ -91,7 +91,11 @@ static void tock_tlp_output (Workspace wptr) {
 			case 0: {
 				uint8_t ch;
 				ChanIn (wptr, in, &ch, sizeof ch);
-				ExternalCallN (fputc, 2, ch, out);
+				if (ch == 255) { // FLUSH
+					fflush (out);
+				} else {
+					ExternalCallN (fputc, 2, ch, out);
+				}
 
 				break;
 			}
diff --git a/testcases/capitalise.occ b/testcases/capitalise.occ
index f1b78bc..b4b6b36 100644
--- a/testcases/capitalise.occ
+++ b/testcases/capitalise.occ
@@ -1,3 +1,5 @@
+#USE "course"
+
 PROC main (CHAN OF BYTE in, out)
   BOOL running:
   SEQ
@@ -13,4 +15,5 @@ PROC main (CHAN OF BYTE in, out)
             out ! b - ('a' - 'A')
           TRUE
             out ! b
+        out ! FLUSH
 :