diff --git a/config.h.in b/config.h.in
index 839483c..bbfb20b 100644
--- a/config.h.in
+++ b/config.h.in
@@ -1123,6 +1123,10 @@
    `CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE', and to 0 if you don't. */
 #undef HAVE_DECL_CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE
 
+/* Define to 1 if you have the declaration of `CURL_HTTP_VERSION_3', and to 0
+   if you don't. */
+#undef HAVE_DECL_CURL_HTTP_VERSION_3
+
 /* Define to 1 if you have the declaration of `CURL_SSLVERSION_TLSv1_0', and
    to 0 if you don't. */
 #undef HAVE_DECL_CURL_SSLVERSION_TLSV1_0
diff --git a/configure b/configure
index 903c79d..14a8a80 100755
--- a/configure
+++ b/configure
@@ -8452,6 +8452,19 @@ fi
 cat >>confdefs.h <<_ACEOF
 #define HAVE_DECL_CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE $ac_have_decl
 _ACEOF
+ac_fn_c_check_decl "$LINENO" "CURL_HTTP_VERSION_3" "ac_cv_have_decl_CURL_HTTP_VERSION_3" "
+#include \"curl/curl.h\"
+
+"
+if test "x$ac_cv_have_decl_CURL_HTTP_VERSION_3" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_CURL_HTTP_VERSION_3 $ac_have_decl
+_ACEOF
 ac_fn_c_check_decl "$LINENO" "CURL_VERSION_TLSAUTH_SRP" "ac_cv_have_decl_CURL_VERSION_TLSAUTH_SRP" "
 #include \"curl/curl.h\"
 
diff --git a/configure.ac b/configure.ac
index ca6b6c6..e8ffb35 100644
--- a/configure.ac
+++ b/configure.ac
@@ -186,7 +186,7 @@ CURLMOPT_MAX_HOST_CONNECTIONS,
 CURL_SSLVERSION_TLSv1_0, CURL_SSLVERSION_TLSv1_1, CURL_SSLVERSION_TLSv1_2, CURL_SSLVERSION_TLSv1_3,
 
 CURL_HTTP_VERSION_2, CURL_HTTP_VERSION_2_0, CURL_HTTP_VERSION_2TLS,
-CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE,
+CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE, CURL_HTTP_VERSION_3,
 
 CURL_VERSION_TLSAUTH_SRP, CURL_VERSION_NTLM_WB],
 [], [],
diff --git a/curl-helper.c b/curl-helper.c
index a010a21..8790fde 100644
--- a/curl-helper.c
+++ b/curl-helper.c
@@ -2039,6 +2039,11 @@ static void handle_HTTP_VERSION(Connection *conn, value option)
     case 5:
 #if HAVE_DECL_CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE
       version = CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE;
+#endif
+      break;
+    case 6:
+#if HAVE_DECL_CURL_HTTP_VERSION_3
+      version = CURL_HTTP_VERSION_3;
 #endif
       break;
     default:
@@ -4505,8 +4510,8 @@ struct used_enum
 
 struct used_enum check_enums[] = {
   { CURLINFO_SSL_DATA_OUT, CURLINFO_END, "DEBUGFUNCTION curl_infotype" },
-#if HAVE_DECL_CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE
-  CURL_ENUM(HTTP_VERSION, 2_PRIOR_KNOWLEDGE),
+#if HAVE_DECL_CURL_HTTP_VERSION_3
+  CURL_ENUM(HTTP_VERSION, 3),
 #endif
 #if HAVE_DECL_CURLINFO_CERTINFO
   { CURLINFO_CERTINFO & CURLINFO_MASK, CURLINFO_LASTONE, "CURLINFO" },
diff --git a/curl.ml b/curl.ml
index 80fea37..dc44273 100644
--- a/curl.ml
+++ b/curl.ml
@@ -166,6 +166,7 @@ type curlHTTPVersion =
   | HTTP_VERSION_2
   | HTTP_VERSION_2TLS
   | HTTP_VERSION_2_PRIOR_KNOWLEDGE
+  | HTTP_VERSION_3
 
 type curlDebugType =
   | DEBUGTYPE_TEXT
diff --git a/curl.mli b/curl.mli
index 10b8876..580329b 100644
--- a/curl.mli
+++ b/curl.mli
@@ -174,6 +174,7 @@ type curlHTTPVersion =
   | HTTP_VERSION_2 (** please use HTTP 2 (requires libcurl >= 7.33.0, otherwise will fallback to libcurl choice) *)
   | HTTP_VERSION_2TLS (** use version 2 for HTTPS, version 1.1 for HTTP (requires libcurl >= 7.47.0) *)
   | HTTP_VERSION_2_PRIOR_KNOWLEDGE (** Issue non-TLS HTTP requests using HTTP/2 without HTTP/1 (requires libcurl >= 7.49.0) *)
+  | HTTP_VERSION_3 (** Makes use of explicit HTTP/3 without fallback. Use CURLOPT_ALTSVC to enable HTTP/3 upgrade (requires libcurl >= 7.66.0) *)
 
 type curlDebugType =
   | DEBUGTYPE_TEXT