diff --git a/res/snmp/agent.c b/res/snmp/agent.c
index 225fb63a76..9633aa173c 100644
--- a/res/snmp/agent.c
+++ b/res/snmp/agent.c
@@ -483,8 +483,8 @@ static u_char *ast_var_channels_table(struct variable *vp, oid *name, size_t *le
 		break;
 	case ASTCHANVARIABLES:
 		if (pbx_builtin_serialize_variables(chan, &out)) {
-			*var_len = strlen(out->str);
-			ret = (u_char *)out->str;
+			*var_len = strlen(ast_str_buffer(out));
+			ret = (u_char *)ast_str_buffer(out);
 		}
 		break;
 	case ASTCHANFLAGS: