1 files changed, 3 insertions, 1 deletions
diff --git a/src/lib/eval.c b/src/lib/eval.c
index 89bdf59..07bbedd 100644
--- a/src/lib/eval.c
+++ b/src/lib/eval.c
@@ -1,7 +1,9 @@
 #include "aplwc_internal.h"
 
-void
+struct aplwc_value *
 eval_line(struct aplwc_line *line)
 {
+	assert(line->aplwc->last_error == APLWC_OK);
 	line->aplwc->last_error = APLWC_NOT_YET_IMPLEMENTED;
+	return NULL;
 }