diff --git a/ChangeLog b/ChangeLog
index c065c915f8..27b505fd37 100755
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,7 @@
 2005-11-08  Kevin P. Fleming  <kpfleming@digium.com>
 
+	* pbx.c (pbx_substitute_variables_helper_full): use already-substituted buffer for parsing variable name (issue #5664)
+
 	* channels/chan_zap.c (zt_request): return AST_CAUSE_CONGESTION when a group-channel is requested and the group exists but all channels are busy (issue #3360, related fix)
 	* channels/chan_iax2.c (create_addr): treat UNREACHABLE as AST_CAUSE_UNREGISTERED so that it will generate CHANUNAVAIL from app_dial (issue #3360)
 
diff --git a/pbx.c b/pbx.c
index e9bbb5f670..8c66db9b53 100755
--- a/pbx.c
+++ b/pbx.c
@@ -1520,7 +1520,7 @@ static void pbx_substitute_variables_helper_full(struct ast_channel *c, struct v
 
 			workspace[0] = '\0';
 
-			parse_variable_name(var, &offset, &offset2, &isfunction);
+			parse_variable_name(vars, &offset, &offset2, &isfunction);
 			if (isfunction) {
 				/* Evaluate function */
 				cp4 = ast_func_read(c, vars, workspace, VAR_BUF_SIZE);