diff --git a/src/core/telemetry_session.cpp b/src/core/telemetry_session.cpp
index cc55915cb..e4248f44c 100644
--- a/src/core/telemetry_session.cpp
+++ b/src/core/telemetry_session.cpp
@@ -35,7 +35,7 @@ static u64 GenerateTelemetryId() {
     mbedtls_entropy_context entropy;
     mbedtls_entropy_init(&entropy);
     mbedtls_ctr_drbg_context ctr_drbg;
-    static constexpr std::array<char, 18> personalization{{"citron Telemetry ID"}};
+    static constexpr std::array<char, 20> personalization{{"citron Telemetry ID"}};
 
     mbedtls_ctr_drbg_init(&ctr_drbg);
     ASSERT(mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy,