diff --git a/docs/cmdline-opts/http2-prior-knowledge.md b/docs/cmdline-opts/http2-prior-knowledge.md
index 7270109417..5dffe26a73 100644
--- a/docs/cmdline-opts/http2-prior-knowledge.md
+++ b/docs/cmdline-opts/http2-prior-knowledge.md
@@ -23,3 +23,7 @@ Issue a non-TLS HTTP requests using HTTP/2 directly without HTTP/1.1 Upgrade.
 It requires prior knowledge that the server supports HTTP/2 straight away.
 HTTPS requests still do HTTP/2 the standard way with negotiated protocol
 version in the TLS handshake.
+
+Since 8.10.0 if this option is set for an HTTPS request then the application
+layer protocol version (ALPN) offered to the server is only HTTP/2. Prior to
+that both HTTP/1.1 and HTTP/2 were offered.
diff --git a/docs/libcurl/opts/CURLOPT_HTTP_VERSION.md b/docs/libcurl/opts/CURLOPT_HTTP_VERSION.md
index 0a9215d8ac..32c2c2ce66 100644
--- a/docs/libcurl/opts/CURLOPT_HTTP_VERSION.md
+++ b/docs/libcurl/opts/CURLOPT_HTTP_VERSION.md
@@ -73,6 +73,10 @@ prior knowledge that the server supports HTTP/2 straight away. HTTPS requests
 still do HTTP/2 the standard way with negotiated protocol version in the TLS
 handshake. (Added in 7.49.0)
 
+Since 8.10.0 if this option is set for an HTTPS request then the application
+layer protocol version (ALPN) offered to the server is only HTTP/2. Prior to
+that both HTTP/1.1 and HTTP/2 were offered.
+
 ## CURL_HTTP_VERSION_3
 
 (Added in 7.66.0) This option makes libcurl attempt to use HTTP/3 to the host
diff --git a/lib/vtls/vtls.c b/lib/vtls/vtls.c
index 442c63d5ff..e778464cf6 100644
--- a/lib/vtls/vtls.c
+++ b/lib/vtls/vtls.c
@@ -138,6 +138,9 @@ static const struct alpn_spec ALPN_SPEC_H11 = {
   { ALPN_HTTP_1_1 }, 1
 };
 #ifdef USE_HTTP2
+static const struct alpn_spec ALPN_SPEC_H2 = {
+  { ALPN_H2 }, 1
+};
 static const struct alpn_spec ALPN_SPEC_H2_H11 = {
   { ALPN_H2, ALPN_HTTP_1_1 }, 2
 };
@@ -148,6 +151,8 @@ static const struct alpn_spec *alpn_get_spec(int httpwant, bool use_alpn)
   if(!use_alpn)
     return NULL;
 #ifdef USE_HTTP2
+  if(httpwant == CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE)
+    return &ALPN_SPEC_H2;
   if(httpwant >= CURL_HTTP_VERSION_2)
     return &ALPN_SPEC_H2_H11;
 #else