diff --git a/src/vmime/security/cert/certificateChain.cpp b/src/vmime/security/cert/certificateChain.cpp
index 3cb4e360..f1154768 100644
--- a/src/vmime/security/cert/certificateChain.cpp
+++ b/src/vmime/security/cert/certificateChain.cpp
@@ -35,13 +35,13 @@ certificateChain::certificateChain(const std::vector <shared_ptr <certificate> >
 }
 
 
-unsigned int certificateChain::getCount() const
+size_t certificateChain::getCount() const
 {
-	return static_cast <unsigned int>(m_certs.size());
+	return m_certs.size();
 }
 
 
-shared_ptr <certificate> certificateChain::getAt(const unsigned int index)
+shared_ptr <certificate> certificateChain::getAt(const size_t index)
 {
 	return m_certs[index];
 }
diff --git a/src/vmime/security/cert/certificateChain.hpp b/src/vmime/security/cert/certificateChain.hpp
index 0ce6bda3..38bf6254 100644
--- a/src/vmime/security/cert/certificateChain.hpp
+++ b/src/vmime/security/cert/certificateChain.hpp
@@ -53,7 +53,7 @@ public:
 	  *
 	  * @return number of certificates in the chain
 	  */
-	unsigned int getCount() const;
+	size_t getCount() const;
 
 	/** Return the certificate at the specified position. 0 is the
 	  * subject certificate, 1 is the issuer's certificate, 2 is
@@ -62,7 +62,7 @@ public:
 	  * @param index position at which to retrieve certificate
 	  * @return certificate at the specified position
 	  */
-	shared_ptr <certificate> getAt(const unsigned int index);
+	shared_ptr <certificate> getAt(const size_t index);
 
 protected:
 
diff --git a/src/vmime/security/cert/defaultCertificateVerifier.cpp b/src/vmime/security/cert/defaultCertificateVerifier.cpp
index 31661617..82e8455a 100644
--- a/src/vmime/security/cert/defaultCertificateVerifier.cpp
+++ b/src/vmime/security/cert/defaultCertificateVerifier.cpp
@@ -76,7 +76,7 @@ void defaultCertificateVerifier::verifyX509
 	// has been issued by the next certificate in the chain
 	if (chain->getCount() >= 2)
 	{
-		for (unsigned int i = 0 ; i < chain->getCount() - 1 ; ++i)
+		for (size_t i = 0 ; i < chain->getCount() - 1 ; ++i)
 		{
 			shared_ptr <X509Certificate> cert =
 				dynamicCast <X509Certificate>(chain->getAt(i));
@@ -96,7 +96,7 @@ void defaultCertificateVerifier::verifyX509
 
 	// For every certificate in the chain, verify that the certificate
 	// is valid at the current time
-	for (unsigned int i = 0 ; i < chain->getCount() ; ++i)
+	for (size_t i = 0 ; i < chain->getCount() ; ++i)
 	{
 		shared_ptr <X509Certificate> cert =
 			dynamicCast <X509Certificate>(chain->getAt(i));
@@ -113,7 +113,7 @@ void defaultCertificateVerifier::verifyX509
 
 	bool trusted = false;
 
-	for (unsigned int i = 0 ; !trusted && i < m_x509RootCAs.size() ; ++i)
+	for (size_t i = 0 ; !trusted && i < m_x509RootCAs.size() ; ++i)
 	{
 		shared_ptr <X509Certificate> rootCa = m_x509RootCAs[i];
 
@@ -127,7 +127,7 @@ void defaultCertificateVerifier::verifyX509
 	shared_ptr <X509Certificate> firstCert =
 		dynamicCast <X509Certificate>(chain->getAt(0));
 
-	for (unsigned int i = 0 ; !trusted && i < m_x509TrustedCerts.size() ; ++i)
+	for (size_t i = 0 ; !trusted && i < m_x509TrustedCerts.size() ; ++i)
 	{
 		shared_ptr <X509Certificate> cert = m_x509TrustedCerts[i];