Index: uspace/app/sbi/src/run_expr.c
===================================================================
--- uspace/app/sbi/src/run_expr.c	(revision 05b5939308a029a5f557f811dd067aa545547cf8)
+++ uspace/app/sbi/src/run_expr.c	(revision 3038d518c8964eb6ceeb13d82eafc07e08a0d630)
@@ -2504,6 +2504,8 @@
 	elem_index = 0;
 
+	assert(node != NULL);
+
 	i = 0;
-	while (node != NULL) {
+	do {
 		if (i >= 1) {
 			printf("Error: Too many indices string.\n");
@@ -2527,5 +2529,5 @@
 		node = list_next(args, node);
 		i += 1;
-	}
+	} while (node != NULL);
 
 	if (i < 1) {