diff --git a/configure.ac b/configure.ac
index 5559409427..6f19a5f4c4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1942,7 +1942,7 @@ if test "x$curl_cv_native_windows" = "xyes" &&
   LIBS="-lbcrypt $LIBS"
 fi
 
-case "x$OPENSSL_ENABLED$GNUTLS_ENABLED$NSS_ENABLED$MBEDTLS_ENABLED$WOLFSSL_ENABLED$SCHANNEL_ENABLED$SECURETRANSPORT_ENABLED$BEARSSL_ENABLED$AMISSL_ENABLED$RUSTLS_ENABLED"
+case "x$OPENSSL_ENABLED$GNUTLS_ENABLED$NSS_ENABLED$MBEDTLS_ENABLED$WOLFSSL_ENABLED$SCHANNEL_ENABLED$SECURETRANSPORT_ENABLED$BEARSSL_ENABLED$RUSTLS_ENABLED"
 in
 x)
   AC_MSG_WARN([SSL disabled, you will not be able to use HTTPS, FTPS, NTLM and more.])
diff --git a/lib/amigaos.c b/lib/amigaos.c
index 6c144095f8..d76f5b03fd 100644
--- a/lib/amigaos.c
+++ b/lib/amigaos.c
@@ -87,38 +87,5 @@ ADD2EXIT(Curl_amiga_cleanup, -50);
 
 #endif /* HAVE_PROTO_BSDSOCKET_H */
 
-#ifdef USE_AMISSL
-void Curl_amiga_X509_free(X509 *a)
-{
-  X509_free(a);
-}
-
-/* AmiSSL replaces many functions with macros. Curl requires pointer
- * to some of these functions. Thus, we have to encapsulate these macros.
- */
-
-#include "warnless.h"
-
-int (SHA256_Init)(SHA256_CTX *c)
-{
-  return SHA256_Init(c);
-};
-
-int (SHA256_Update)(SHA256_CTX *c, const void *data, size_t len)
-{
-  return SHA256_Update(c, data, curlx_uztoui(len));
-};
-
-int (SHA256_Final)(unsigned char *md, SHA256_CTX *c)
-{
-  return SHA256_Final(md, c);
-};
-
-void (X509_INFO_free)(X509_INFO *a)
-{
-  X509_INFO_free(a);
-};
-
-#endif /* USE_AMISSL */
 #endif /* __AMIGA__ */
 
diff --git a/lib/amigaos.h b/lib/amigaos.h
index 8757aa8e73..5255194dc7 100644
--- a/lib/amigaos.h
+++ b/lib/amigaos.h
@@ -37,10 +37,5 @@ void Curl_amiga_cleanup();
 
 #endif
 
-#ifdef USE_AMISSL
-#include <openssl/x509v3.h>
-void Curl_amiga_X509_free(X509 *a);
-#endif /* USE_AMISSL */
-
 #endif /* HEADER_CURL_AMIGAOS_H */
 
diff --git a/lib/md4.c b/lib/md4.c
index 63bade00df..e976fe7bdc 100644
--- a/lib/md4.c
+++ b/lib/md4.c
@@ -32,7 +32,8 @@
 
 #ifdef USE_OPENSSL
 #include <openssl/opensslconf.h>
-#if defined(OPENSSL_VERSION_MAJOR) && (OPENSSL_VERSION_MAJOR >= 3)
+#if defined(OPENSSL_VERSION_MAJOR) && (OPENSSL_VERSION_MAJOR >= 3) && \
+   !defined(USE_AMISSL)
 /* OpenSSL 3.0.0 marks the MD4 functions as deprecated */
 #define OPENSSL_NO_MD4
 #endif
diff --git a/lib/md5.c b/lib/md5.c
index 2164e15ff2..5be639929d 100644
--- a/lib/md5.c
+++ b/lib/md5.c
@@ -41,7 +41,7 @@
 #endif
 #endif /* USE_MBEDTLS */
 
-#if defined(USE_OPENSSL) && !defined(USE_AMISSL)
+#ifdef USE_OPENSSL
   #include <openssl/opensslconf.h>
   #if !defined(OPENSSL_NO_MD5) && !defined(OPENSSL_NO_DEPRECATED_3_0)
     #define USE_OPENSSL_MD5
diff --git a/lib/vtls/openssl.c b/lib/vtls/openssl.c
index 25e065d6cb..5a7a612407 100644
--- a/lib/vtls/openssl.c
+++ b/lib/vtls/openssl.c
@@ -78,10 +78,6 @@
 #include <openssl/buffer.h>
 #include <openssl/pkcs12.h>
 
-#ifdef USE_AMISSL
-#include "amigaos.h"
-#endif
-
 #if (OPENSSL_VERSION_NUMBER >= 0x0090808fL) && !defined(OPENSSL_NO_OCSP)
 #include <openssl/ocsp.h>
 #endif
@@ -996,11 +992,7 @@ int cert_stuff(struct Curl_easy *data,
   fail:
       EVP_PKEY_free(pri);
       X509_free(x509);
-#ifdef USE_AMISSL
-      sk_X509_pop_free(ca, Curl_amiga_X509_free);
-#else
       sk_X509_pop_free(ca, X509_free);
-#endif
       if(!cert_done)
         return 0; /* failure! */
       break;
diff --git a/m4/curl-amissl.m4 b/m4/curl-amissl.m4
index df07bdb295..dfa626da93 100644
--- a/m4/curl-amissl.m4
+++ b/m4/curl-amissl.m4
@@ -23,21 +23,46 @@
 #***************************************************************************
 
 AC_DEFUN([CURL_WITH_AMISSL], [
-AC_MSG_CHECKING([whether to enable Amiga native SSL/TLS (AmiSSL)])
+AC_MSG_CHECKING([whether to enable Amiga native SSL/TLS (AmiSSL v5)])
 if test "$HAVE_PROTO_BSDSOCKET_H" = "1"; then
   if test "x$OPT_AMISSL" != xno; then
     ssl_msg=
-    if test "x$OPT_AMISSL" != "xno"; then
-      AC_MSG_RESULT(yes)
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        #include <libraries/amisslmaster.h>
+        #include <openssl/opensslv.h>
+      ]],[[
+        #if defined(AMISSL_CURRENT_VERSION) && (AMISSL_CURRENT_VERSION >= AMISSL_V303) && \
+            defined(OPENSSL_VERSION_MAJOR) && (OPENSSL_VERSION_MAJOR >= 3) && \
+            defined(PROTO_AMISSL_H)
+        return 0;
+        #else
+        #error not AmiSSL v5 / OpenSSL 3
+        #endif
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
       ssl_msg="AmiSSL"
       test amissl != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
       AMISSL_ENABLED=1
-      LIBS="-lamisslauto $LIBS"
+      OPENSSL_ENABLED=1
+      # Use AmiSSL's built-in ca bundle
+      check_for_ca_bundle=1
+      with_ca_fallback=yes
+      LIBS="-lamisslstubs -lamisslauto $LIBS"
       AC_DEFINE(USE_AMISSL, 1, [if AmiSSL is in use])
       AC_DEFINE(USE_OPENSSL, 1, [if OpenSSL is in use])
-    else
-      AC_MSG_RESULT(no)
-    fi
+      AC_DEFINE_UNQUOTED(HAVE_OPENSSL3, 1, [Define to 1 if using OpenSSL 3 or later.])
+      AC_CHECK_HEADERS(openssl/x509.h openssl/rsa.h openssl/crypto.h \
+                       openssl/pem.h openssl/ssl.h openssl/err.h)
+      dnl OpenSSLv3 marks the DES functions deprecated but we have no
+      dnl replacements (yet) so tell the compiler to not warn for them
+      dnl
+      dnl Ask OpenSSL to suppress the warnings.
+      CPPFLAGS="$CPPFLAGS -DOPENSSL_SUPPRESS_DEPRECATED"
+    ],[
+      AC_MSG_RESULT([no])
+    ])
     test -z "$ssl_msg" || ssl_backends="${ssl_backends:+$ssl_backends, }$ssl_msg"
   else
     AC_MSG_RESULT(no)