diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index 9a98d87d21..5ebd9979eb 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -1743,7 +1743,7 @@ __owur long SSL_get_default_timeout(const SSL *s);
 #endif
 
 __owur char *SSL_CIPHER_description(const SSL_CIPHER *, char *buf, int size);
-__owur STACK_OF(X509_NAME) *SSL_dup_CA_list(STACK_OF(X509_NAME) *sk);
+__owur STACK_OF(X509_NAME) *SSL_dup_CA_list(const STACK_OF(X509_NAME) *sk);
 
 __owur SSL *SSL_dup(SSL *ssl);
 
diff --git a/ssl/ssl_cert.c b/ssl/ssl_cert.c
index 95dde8517d..a4e7977012 100644
--- a/ssl/ssl_cert.c
+++ b/ssl/ssl_cert.c
@@ -466,7 +466,7 @@ static void set0_CA_list(STACK_OF(X509_NAME) **ca_list,
     *ca_list = name_list;
 }
 
-STACK_OF(X509_NAME) *SSL_dup_CA_list(STACK_OF(X509_NAME) *sk)
+STACK_OF(X509_NAME) *SSL_dup_CA_list(const STACK_OF(X509_NAME) *sk)
 {
     int i;
     STACK_OF(X509_NAME) *ret;