diff --git a/src/datenklo/datenklo.c b/src/datenklo/datenklo.c
index 13331d6..e62edbf 100644
--- a/src/datenklo/datenklo.c
+++ b/src/datenklo/datenklo.c
@@ -1001,7 +1001,7 @@ static ssize_t dk_ioctl_set(void *inst, int cmd, const void *buf, size_t in_bufs
 			break;
 		case TCOON:
 			PDEBUG(DDATENKLO, DEBUG_DEBUG, "Terminal turns on output.\n");
-			datenklo->output_off = 1;
+			datenklo->output_off = 0;
 			break;
 		case TCIOFF:
 			PDEBUG(DDATENKLO, DEBUG_DEBUG, "Terminal turns off input.\n");