diff --git a/rtc_base/openssladapter.h b/rtc_base/openssladapter.h
index e77575e129..2e3a355f43 100644
--- a/rtc_base/openssladapter.h
+++ b/rtc_base/openssladapter.h
@@ -32,7 +32,7 @@
 
 namespace rtc {
 
-class OpenSSLAdapter : public SSLAdapter, public MessageHandler {
+class OpenSSLAdapter final : public SSLAdapter, public MessageHandler {
  public:
   static bool InitializeSSL();
   static bool CleanupSSL();
diff --git a/rtc_base/opensslcertificate.h b/rtc_base/opensslcertificate.h
index 40de0216c4..088725c0d7 100644
--- a/rtc_base/opensslcertificate.h
+++ b/rtc_base/opensslcertificate.h
@@ -28,7 +28,7 @@ class OpenSSLKeyPair;
 
 // OpenSSLCertificate encapsulates an OpenSSL X509* certificate object,
 // which is also reference counted inside the OpenSSL library.
-class OpenSSLCertificate : public SSLCertificate {
+class OpenSSLCertificate final : public SSLCertificate {
  public:
   // X509 object has its reference count incremented. So the caller and
   // OpenSSLCertificate share ownership.
diff --git a/rtc_base/openssldigest.h b/rtc_base/openssldigest.h
index 78986f5af7..82dc9a96cd 100644
--- a/rtc_base/openssldigest.h
+++ b/rtc_base/openssldigest.h
@@ -20,7 +20,7 @@
 namespace rtc {
 
 // An implementation of the digest class that uses OpenSSL.
-class OpenSSLDigest : public MessageDigest {
+class OpenSSLDigest final : public MessageDigest {
  public:
   // Creates an OpenSSLDigest with |algorithm| as the hash algorithm.
   explicit OpenSSLDigest(const std::string& algorithm);
diff --git a/rtc_base/opensslidentity.h b/rtc_base/opensslidentity.h
index 21bee91d36..fcf7debf90 100644
--- a/rtc_base/opensslidentity.h
+++ b/rtc_base/opensslidentity.h
@@ -27,7 +27,7 @@ namespace rtc {
 
 // OpenSSLKeyPair encapsulates an OpenSSL EVP_PKEY* keypair object,
 // which is reference counted inside the OpenSSL library.
-class OpenSSLKeyPair {
+class OpenSSLKeyPair final {
  public:
   explicit OpenSSLKeyPair(EVP_PKEY* pkey) : pkey_(pkey) {
     RTC_DCHECK(pkey_ != nullptr);
@@ -58,7 +58,7 @@ class OpenSSLKeyPair {
 
 // Holds a keypair and certificate together, and a method to generate
 // them consistently.
-class OpenSSLIdentity : public SSLIdentity {
+class OpenSSLIdentity final : public SSLIdentity {
  public:
   static OpenSSLIdentity* GenerateWithExpiration(const std::string& common_name,
                                                  const KeyParams& key_params,
diff --git a/rtc_base/opensslstreamadapter.h b/rtc_base/opensslstreamadapter.h
index 927fe2bde5..358f7f3166 100644
--- a/rtc_base/opensslstreamadapter.h
+++ b/rtc_base/opensslstreamadapter.h
@@ -56,7 +56,7 @@ class SSLCertChain;
 
 ///////////////////////////////////////////////////////////////////////////////
 
-class OpenSSLStreamAdapter : public SSLStreamAdapter {
+class OpenSSLStreamAdapter final : public SSLStreamAdapter {
  public:
   explicit OpenSSLStreamAdapter(StreamInterface* stream);
   ~OpenSSLStreamAdapter() override;