diff --git a/ChangeLog b/ChangeLog
index 2018592..8197664 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,6 @@
+08/01/2019
+- fix cfg->accept_source_token_in initialization
+
 07/17/2019
 - add r->user to sts_hander
 
diff --git a/src/sts.c b/src/sts.c
index 1132dc5..424984f 100644
--- a/src/sts.c
+++ b/src/sts.c
@@ -453,6 +453,9 @@ const char *sts_cfg_set_accept_source_token_in(oauth2_sts_cfg_t *cfg,
 					       const char *type,
 					       const char *options)
 {
+	if (cfg->accept_source_token_in == NULL)
+		cfg->accept_source_token_in =
+		    oauth2_cfg_source_token_init(NULL);
 	return oauth2_cfg_source_token_set_accept_in(
 	    NULL, cfg->accept_source_token_in, type, options);
 }