diff --git a/configure.ac b/configure.ac
index 973394bce..31fc8ffb7 100755
--- a/configure.ac
+++ b/configure.ac
@@ -1873,6 +1873,31 @@ if test -z "$ssl_backends" -o "x$OPT_SSL" != xno &&
     ],[
       AC_MSG_RESULT([no])
     ])
+
+    AC_MSG_CHECKING([for OpenSSL >= v3])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+#include <openssl/opensslv.h>
+      ]],[[
+        #if defined(OPENSSL_VERSION_MAJOR) && (OPENSSL_VERSION_MAJOR >= 3)
+        return 0;
+        #else
+        #error older than 3
+        #endif
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      AC_DEFINE_UNQUOTED(HAVE_OPENSSL3, 1,
+        [Define to 1 if using OpenSSL 3 or later.])
+      dnl OpenSSLv3 marks the DES functions deprecated but we have no
+      dnl replacements (yet) so tell the compiler to not warn for them
+      dnl
+      dnl Ask OpenSSL to suppress the warnings.
+      CPPFLAGS="$CPPFLAGS -DOPENSSL_SUPPRESS_DEPRECATED"
+      ssl_msg="OpenSSL v3+"
+    ],[
+      AC_MSG_RESULT([no])
+    ])
   fi
 
   if test "$OPENSSL_ENABLED" = "1"; then
diff --git a/lib/md4.c b/lib/md4.c
index 4dab6af7a..10e6fc537 100644
--- a/lib/md4.c
+++ b/lib/md4.c
@@ -29,6 +29,10 @@
 
 #ifdef USE_OPENSSL
 #include <openssl/opensslconf.h>
+#if defined(OPENSSL_VERSION_MAJOR) && (OPENSSL_VERSION_MAJOR >= 3)
+/* OpenSSL 3.0.0 marks the MD4 functions as deprecated */
+#define OPENSSL_NO_MD4
+#endif
 #endif /* USE_OPENSSL */
 
 #ifdef USE_MBEDTLS
diff --git a/lib/vtls/openssl.c b/lib/vtls/openssl.c
index ece655133..14bfe3562 100644
--- a/lib/vtls/openssl.c
+++ b/lib/vtls/openssl.c
@@ -2719,6 +2719,33 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
   }
 #endif
 
+#if defined(OPENSSL_VERSION_MAJOR) && (OPENSSL_VERSION_MAJOR >= 3)
+  /* OpenSSL 3.0.0 has deprecated SSL_CTX_load_verify_locations */
+  if(ssl_cafile) {
+    if(!SSL_CTX_load_verify_file(backend->ctx, ssl_cafile)) {
+      if(verifypeer) {
+        /* Fail if we insist on successfully verifying the server. */
+        failf(data, "error setting certificate file: %s", ssl_cafile);
+        return CURLE_SSL_CACERT_BADFILE;
+      }
+      /* Continue with a warning if no certificate verification is required. */
+      infof(data, "error setting certificate file, continuing anyway\n");
+    }
+    infof(data, "  CAfile: %s\n", ssl_cafile);
+  }
+  if(ssl_capath) {
+    if(!SSL_CTX_load_verify_dir(backend->ctx, ssl_capath)) {
+      if(verifypeer) {
+        /* Fail if we insist on successfully verifying the server. */
+        failf(data, "error setting certificate path: %s", ssl_capath);
+        return CURLE_SSL_CACERT_BADFILE;
+      }
+      /* Continue with a warning if no certificate verification is required. */
+      infof(data, "error setting certificate path, continuing anyway\n");
+    }
+    infof(data, "  CApath: %s\n", ssl_capath);
+  }
+#else
   if(ssl_cafile || ssl_capath) {
     /* tell SSL where to find CA certificates that are used to verify
        the servers certificate. */
@@ -2746,6 +2773,8 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
           ssl_cafile ? ssl_cafile : "none",
           ssl_capath ? ssl_capath : "none");
   }
+#endif
+
 #ifdef CURL_CA_FALLBACK
   else if(verifypeer) {
     /* verifying the peer without any CA certificates won't