diff --git a/libamqpprox/amqpprox_tlsutil.cpp b/libamqpprox/amqpprox_tlsutil.cpp
index c3a2b9f..9331d02 100644
--- a/libamqpprox/amqpprox_tlsutil.cpp
+++ b/libamqpprox/amqpprox_tlsutil.cpp
@@ -82,15 +82,35 @@ void TlsUtil::logTlsConnectionAlert(const SSL *s, int where, int ret)
 bool TlsUtil::logCertVerificationFailure(bool preverified,
                                          boost::asio::ssl::verify_context &ctx)
 {
-    if (!preverified) {
-        char  subject_name[256];
-        X509 *cert = X509_STORE_CTX_get_current_cert(ctx.native_handle());
-        X509_NAME_oneline(X509_get_subject_name(cert), subject_name, 255);
+    if (preverified) {
+        return preverified;
+    }
+
+    X509_STORE_CTX *storeCtx = ctx.native_handle();
+
+    if (!storeCtx) {
+        LOG_ERROR << "Certificate verification failed: no verification "
+                     "context available";
+        return preverified;
+    }
 
-        LOG_ERROR << "Certificate verification failed: [" << subject_name
-                  << "]: ";
+    const int errorCode  = X509_STORE_CTX_get_error(storeCtx);
+    const int errorDepth = X509_STORE_CTX_get_error_depth(storeCtx);
+
+    X509      *cert    = X509_STORE_CTX_get_current_cert(storeCtx);
+    X509_NAME *subject = cert ? X509_get_subject_name(cert) : nullptr;
+
+    char subjectName[256] = "unavailable";
+
+    if (subject) {
+        X509_NAME_oneline(subject, subjectName, sizeof(subjectName));
     }
 
+    LOG_ERROR << "Certificate verification failed: subjectName=" << subjectName
+              << " errorCode=" << errorCode
+              << " errorString=" << X509_verify_cert_error_string(errorCode)
+              << " depth=" << errorDepth;
+
     return preverified;
 }
 
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 3d801a6..92e8da0 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -41,6 +41,7 @@ add_executable(amqpprox_tests
     amqpprox_sessionstate.t.cpp
     amqpprox_statcollector.t.cpp
     amqpprox_statsnapshot.t.cpp
+    amqpprox_tlsutil.t.cpp
     amqpprox_types.t.cpp
     amqpprox_vhoststate.t.cpp
     )
diff --git a/tests/amqpprox_tlsutil.t.cpp b/tests/amqpprox_tlsutil.t.cpp
new file mode 100644
index 0000000..86412cc
--- /dev/null
+++ b/tests/amqpprox_tlsutil.t.cpp
@@ -0,0 +1,125 @@
+/*
+** Copyright 2026 Bloomberg Finance L.P.
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+
+#include <amqpprox_tlsutil.h>
+
+#include <gtest/gtest.h>
+
+#include <boost/asio/ssl.hpp>
+
+#include <openssl/x509.h>
+#include <openssl/x509_vfy.h>
+
+using namespace Bloomberg;
+using namespace amqpprox;
+
+namespace {
+
+class StoreContextGuard {
+    X509_STORE_CTX *d_ctx;
+
+  public:
+    StoreContextGuard()
+    : d_ctx(X509_STORE_CTX_new())
+    {
+    }
+
+    ~StoreContextGuard()
+    {
+        if (d_ctx) {
+            X509_STORE_CTX_free(d_ctx);
+        }
+    }
+
+    StoreContextGuard(const StoreContextGuard &)            = delete;
+    StoreContextGuard &operator=(const StoreContextGuard &) = delete;
+
+    X509_STORE_CTX *get() { return d_ctx; }
+};
+
+class CertificateGuard {
+    X509 *d_cert;
+
+  public:
+    CertificateGuard()
+    : d_cert(X509_new())
+    {
+    }
+
+    ~CertificateGuard()
+    {
+        if (d_cert) {
+            X509_free(d_cert);
+        }
+    }
+
+    CertificateGuard(const CertificateGuard &)            = delete;
+    CertificateGuard &operator=(const CertificateGuard &) = delete;
+
+    X509 *get() { return d_cert; }
+};
+
+}
+
+TEST(TlsUtil, LogCertVerificationFailureNullCurrentCert)
+{
+    StoreContextGuard storeCtx;
+    ASSERT_NE(storeCtx.get(), nullptr);
+    ASSERT_EQ(X509_STORE_CTX_init(storeCtx.get(), nullptr, nullptr, nullptr),
+              1);
+    ASSERT_EQ(X509_STORE_CTX_get_current_cert(storeCtx.get()), nullptr);
+
+    boost::asio::ssl::verify_context ctx(storeCtx.get());
+
+    EXPECT_FALSE(TlsUtil::logCertVerificationFailure(false, ctx));
+}
+
+TEST(TlsUtil, LogCertVerificationFailureNullStoreContext)
+{
+    boost::asio::ssl::verify_context ctx(nullptr);
+
+    EXPECT_FALSE(TlsUtil::logCertVerificationFailure(false, ctx));
+}
+
+TEST(TlsUtil, LogCertVerificationFailureWithSubject)
+{
+    StoreContextGuard storeCtx;
+    ASSERT_NE(storeCtx.get(), nullptr);
+    ASSERT_EQ(X509_STORE_CTX_init(storeCtx.get(), nullptr, nullptr, nullptr),
+              1);
+
+    CertificateGuard cert;
+    ASSERT_NE(cert.get(), nullptr);
+    ASSERT_NE(X509_get_subject_name(cert.get()), nullptr);
+
+    X509_STORE_CTX_set_current_cert(storeCtx.get(), cert.get());
+
+    boost::asio::ssl::verify_context ctx(storeCtx.get());
+
+    EXPECT_FALSE(TlsUtil::logCertVerificationFailure(false, ctx));
+}
+
+TEST(TlsUtil, LogCertVerificationPreverifiedPassesThrough)
+{
+    StoreContextGuard storeCtx;
+    ASSERT_NE(storeCtx.get(), nullptr);
+    ASSERT_EQ(X509_STORE_CTX_init(storeCtx.get(), nullptr, nullptr, nullptr),
+              1);
+
+    boost::asio::ssl::verify_context ctx(storeCtx.get());
+
+    EXPECT_TRUE(TlsUtil::logCertVerificationFailure(true, ctx));
+}