diff --git a/src/tpm.c b/src/tpm.c
index b92ba16..bd439a5 100644
--- a/src/tpm.c
+++ b/src/tpm.c
@@ -141,6 +141,8 @@ int tpm_pay(void* fc, tolling_info_t* info, void* security_socket, uint8_t* neig
                 asn_enc_rval_t e_tep = uper_encode_to_buffer(&asn_DEF_TPM, NULL, tolling->station.obu.entry_proof, b_tep, 1024);
                 if (e_tep.encoded == -1) {
                     syslog_err("[facilities] [tolling] error encoding TPM entry proof (%s)", e_tep.failed_type->name);
+                    ASN_STRUCT_FREE(asn_DEF_TPM, tolling->station.obu.entry_proof);
+                    tolling->station.obu.entry_proof = NULL;
                     rv = 1;
                     goto cleanup;
                 }