diff --git a/ChangeLog.d/fix-session-copy-bug.txt b/ChangeLog.d/fix-session-copy-bug.txt
new file mode 100644
index 0000000000..46e3d8ef61
--- /dev/null
+++ b/ChangeLog.d/fix-session-copy-bug.txt
@@ -0,0 +1,6 @@
+Bugfix
+   * Fix a double-free that happened after mbedtls_ssl_set_session() or
+     mbedtls_ssl_get_session() failed with MBEDTLS_ERR_SSL_ALLOC_FAILED
+     (out of memory). After that, calling mbedtls_ssl_session_free()
+     and mbedtls_ssl_free() would cause an internal session buffer to
+     be free()'d twice.
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index ae8f34ec9c..127276486b 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -301,6 +301,10 @@ static int ssl_session_copy( mbedtls_ssl_session *dst, const mbedtls_ssl_session
     mbedtls_ssl_session_free( dst );
     memcpy( dst, src, sizeof( mbedtls_ssl_session ) );
 
+#if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
+    dst->ticket = NULL;
+#endif
+
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
     if( src->peer_cert != NULL )
     {