diff --git a/doc/configuration.txt b/doc/configuration.txt
index 6728644..a21e0fc 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -4122,8 +4122,9 @@
   ('`'), 123 ('{'), 124 ('|'), 125 ('}'), 127 (delete) and anything above are
   not allowed at all. Haproxy always blocks a number of them (0..32, 127). The
   remaining ones are blocked by default unless this option is enabled. This
-  option also relaxes the test on the HTTP version format, it allows multiple
-  digits for both the major and the minor version.
+  option also relaxes the test on the HTTP version, it allows HTTP/0.9 requests
+  to pass through (no version specified) and multiple digits for both the major
+  and the minor version.
 
   This option should never be enabled by default as it hides application bugs
   and open security breaches. It should only be deployed after a problem has
diff --git a/src/proto_http.c b/src/proto_http.c
index a0c9e1c..606aebd 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -2939,10 +2939,6 @@
 		}
 	}
 
-	/* 4. We may have to convert HTTP/0.9 requests to HTTP/1.0 */
-	if (unlikely(msg->sl.rq.v_l == 0) && !http_upgrade_v09_to_v10(txn))
-		goto return_bad_req;
-
 	/* RFC7230#2.6 has enforced the format of the HTTP version string to be
 	 * exactly one digit "." one digit. This check may be disabled using
 	 * option accept-invalid-http-request.
@@ -2961,6 +2957,11 @@
 			goto return_bad_req;
 		}
 	}
+	else {
+		/* 4. We may have to convert HTTP/0.9 requests to HTTP/1.0 */
+		if (unlikely(msg->sl.rq.v_l == 0) && !http_upgrade_v09_to_v10(txn))
+			goto return_bad_req;
+	}
 
 	/* ... and check if the request is HTTP/1.1 or above */
 	if ((msg->sl.rq.v_l == 8) &&