diff --git a/src/tree.c b/src/tree.c
index 10bf1e9..99c447e 100644
--- a/src/tree.c
+++ b/src/tree.c
@@ -4,7 +4,7 @@
 int libab_tree_has_vector(libab_tree_variant variant) {
     return variant == BASE || variant == OP ||
             variant == UNARY_OP || variant == BLOCK ||
-            variant == IF;
+            variant == IF || variant == CALL;
 }
 
 int libab_tree_has_string(libab_tree_variant variant) {