diff --git a/sdk/identity/azure-identity/inc/azure/identity/client_certificate_credential.hpp b/sdk/identity/azure-identity/inc/azure/identity/client_certificate_credential.hpp
index 4cc6e253c..8255cb91c 100644
--- a/sdk/identity/azure-identity/inc/azure/identity/client_certificate_credential.hpp
+++ b/sdk/identity/azure-identity/inc/azure/identity/client_certificate_credential.hpp
@@ -99,8 +99,8 @@ namespace Azure { namespace Identity {
     explicit ClientCertificateCredential(
         std::string tenantId,
         std::string const& clientId,
-        std::string clientCertificate,
-        std::string privateKey,
+        std::string const& clientCertificate,
+        std::string const& privateKey,
         std::string const& authorityHost,
         std::vector<std::string> additionallyAllowedTenants,
         bool sendCertificateChain,
@@ -137,8 +137,8 @@ namespace Azure { namespace Identity {
     explicit ClientCertificateCredential(
         std::string tenantId,
         std::string const& clientId,
-        std::string clientCertificate,
-        std::string privateKey,
+        std::string const& clientCertificate,
+        std::string const& privateKey,
         ClientCertificateCredentialOptions const& options = {});
 
     /**
diff --git a/sdk/identity/azure-identity/src/client_certificate_credential.cpp b/sdk/identity/azure-identity/src/client_certificate_credential.cpp
index e566ca6c0..ec84b1fd4 100644
--- a/sdk/identity/azure-identity/src/client_certificate_credential.cpp
+++ b/sdk/identity/azure-identity/src/client_certificate_credential.cpp
@@ -322,8 +322,8 @@ UniquePrivateKey ImportPemPrivateKey(std::string const& pem)
 }
 
 std::tuple<CertificateThumbprint, UniquePrivateKey> ReadPemCertificate(
-    std::string clientCertificate,
-    std::string privateKey)
+    std::string const& clientCertificate,
+    std::string const& privateKey)
 {
   auto certContext = ImportPemCertificate(clientCertificate);
 
@@ -422,8 +422,8 @@ std::tuple<CertificateThumbprint, UniquePrivateKey> GetThumbprintAndKey(
 }
 
 std::tuple<CertificateThumbprint, UniquePrivateKey> ReadPemCertificate(
-    std::string clientCertificate,
-    std::string privateKey)
+    std::string const& clientCertificate,
+    std::string const& privateKey)
 {
   // Create a BIO from the private key vector data in memory.
   UniqueHandle<BIO> bioKey(BIO_new_mem_buf(privateKey.data(), static_cast<int>(privateKey.size())));
@@ -585,8 +585,8 @@ ClientCertificateCredential::ClientCertificateCredential(
 ClientCertificateCredential::ClientCertificateCredential(
     std::string tenantId,
     std::string const& clientId,
-    std::string clientCertificate,
-    std::string privateKey,
+    std::string const& clientCertificate,
+    std::string const& privateKey,
     std::string const& authorityHost,
     std::vector<std::string> additionallyAllowedTenants,
     bool sendCertificateChain,
@@ -655,8 +655,8 @@ ClientCertificateCredential::ClientCertificateCredential(
 ClientCertificateCredential::ClientCertificateCredential(
     std::string tenantId,
     std::string const& clientId,
-    std::string clientCertificate,
-    std::string privateKey,
+    std::string const& clientCertificate,
+    std::string const& privateKey,
     ClientCertificateCredentialOptions const& options)
     : ClientCertificateCredential(
         tenantId,