diff --git a/Sources/CTunnelKitOpenVPNProtocol/CryptoCBC.m b/Sources/CTunnelKitOpenVPNProtocol/CryptoCBC.m
index 80d085c..cc2dcad 100644
--- a/Sources/CTunnelKitOpenVPNProtocol/CryptoCBC.m
+++ b/Sources/CTunnelKitOpenVPNProtocol/CryptoCBC.m
@@ -50,8 +50,8 @@ const NSInteger CryptoCBCMaxHMACLength = 100;
 
 @property (nonatomic, unsafe_unretained) const EVP_CIPHER *cipher;
 @property (nonatomic, unsafe_unretained) const EVP_MD *digest;
-@property (nonatomic, unsafe_unretained) const char *utfCipherName;
-@property (nonatomic, unsafe_unretained) const char *utfDigestName;
+@property (nonatomic, unsafe_unretained) char *utfCipherName;
+@property (nonatomic, unsafe_unretained) char *utfDigestName;
 @property (nonatomic, assign) int cipherKeyLength;
 @property (nonatomic, assign) int cipherIVLength;
 @property (nonatomic, assign) int hmacKeyLength;
diff --git a/Sources/CTunnelKitOpenVPNProtocol/CryptoCTR.m b/Sources/CTunnelKitOpenVPNProtocol/CryptoCTR.m
index 4d1da30..0d19820 100644
--- a/Sources/CTunnelKitOpenVPNProtocol/CryptoCTR.m
+++ b/Sources/CTunnelKitOpenVPNProtocol/CryptoCTR.m
@@ -38,8 +38,8 @@ static const NSInteger CryptoCTRTagLength = 32;
 
 @property (nonatomic, unsafe_unretained) const EVP_CIPHER *cipher;
 @property (nonatomic, unsafe_unretained) const EVP_MD *digest;
-@property (nonatomic, unsafe_unretained) const char *utfCipherName;
-@property (nonatomic, unsafe_unretained) const char *utfDigestName;
+@property (nonatomic, unsafe_unretained) char *utfCipherName;
+@property (nonatomic, unsafe_unretained) char *utfDigestName;
 @property (nonatomic, assign) int cipherKeyLength;
 @property (nonatomic, assign) int cipherIVLength;
 @property (nonatomic, assign) int hmacKeyLength;