1 files changed, 1 insertions, 0 deletions

diff --git a/src/ccl.h b/src/ccl.h
index 5965b74155a..0a784448f02 100644
--- a/src/ccl.h
+++ b/src/ccl.h
@@ -52,6 +52,7 @@ struct ccl_program {
   int buf_magnification;        /* Output buffer magnification.  How
                                    many times bigger the output buffer
                                    should be than the input buffer.  */
+  int stack_idx;                /* How deep the call of CCL_Call is nested.  */
 };
 
 /* This data type is used for the spec field of the structure