diff --git a/draft-ietf-httpbis-messaging-latest.html b/draft-ietf-httpbis-messaging-latest.html
index cb935555a..245c15538 100644
--- a/draft-ietf-httpbis-messaging-latest.html
+++ b/draft-ietf-httpbis-messaging-latest.html
@@ -582,7 +582,7 @@
        content: "Fielding, et al.";
   }
   @bottom-center {
-       content: "Expires September 23, 2019";
+       content: "Expires September 27, 2019";
   }
   @bottom-right {
        content: "[Page " counter(page) "]";
@@ -628,7 +628,7 @@
       <meta name="dcterms.creator" content="Fielding, R.">
       <meta name="dcterms.creator" content="Nottingham, M.">
       <meta name="dcterms.creator" content="Reschke, J. F.">
-      <meta name="dcterms.issued" content="2019-03-22">
+      <meta name="dcterms.issued" content="2019-03-26">
       <meta name="dct.replaces" content="urn:ietf:rfc:7230">
       <meta name="dcterms.abstract" content="The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypertext information systems. This document specifies the HTTP/1.1 message syntax, message parsing, connection management, and related security concerns. This document obsoletes portions of RFC 7230.">
       <meta name="description" content="The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypertext information systems. This document specifies the HTTP/1.1 message syntax, message parsing, connection management, and related security concerns. This document obsoletes portions of RFC 7230.">
@@ -655,7 +655,7 @@
                   <td class="right">Fastly</td>
                </tr>
                <tr>
-                  <td class="left">Expires: September 23, 2019</td>
+                  <td class="left">Expires: September 27, 2019</td>
                   <td class="right">J. Reschke, Editor</td>
                </tr>
                <tr>
@@ -664,7 +664,7 @@
                </tr>
                <tr>
                   <td class="left"></td>
-                  <td class="right">March 22, 2019</td>
+                  <td class="right">March 26, 2019</td>
                </tr>
             </tbody>
          </table>
@@ -718,7 +718,7 @@ <h2><a href="#rfc.status">Status of This Memo</a></h2>
                Internet-Drafts as reference material or to cite them other than as “work in progress”.<a class="self" href="#rfc.boilerplate.1.p.3">¶</a></p>
          </div>
          <div id="rfc.boilerplate.1.p.4">
-            <p>This Internet-Draft will expire on September 23, 2019.<a class="self" href="#rfc.boilerplate.1.p.4">¶</a></p>
+            <p>This Internet-Draft will expire on September 27, 2019.<a class="self" href="#rfc.boilerplate.1.p.4">¶</a></p>
          </div>
       </section>
       <section id="rfc.copyrightnotice">
@@ -1317,10 +1317,9 @@ <h3 id="rfc.section.3.3"><a href="#rfc.section.3.3">3.3.</a>&nbsp;<a href="#h1.e
          <h2 id="rfc.section.4"><a href="#rfc.section.4">4.</a>&nbsp;<a href="#status.line">Status Line</a></h2>
          <div id="rfc.section.4.p.1">
             <p>The first line of a response message is the status-line, consisting of the protocol
-               version, a space (SP), the status code, another space, a possibly empty textual phrase
-               describing the status code, and ending with CRLF.<a class="self" href="#rfc.section.4.p.1">¶</a></p>
+               version, a space (SP), the status code, another space, an <em class="bcp14">OPTIONAL</em> textual phrase describing the status code, and ending with CRLF.<a class="self" href="#rfc.section.4.p.1">¶</a></p>
          </div>
-         <div id="rfc.section.4.p.2"><pre class="inline prettyprint lang-ietf_abnf"><span id="rfc.iref.g.16"></span>  <a href="#status.line" class="smpl">status-line</a> = <a href="#http.version" class="smpl">HTTP-version</a> <a href="#core.rules" class="smpl">SP</a> <a href="#status.line" class="smpl">status-code</a> <a href="#core.rules" class="smpl">SP</a> <a href="#status.line" class="smpl">reason-phrase</a> <a href="#core.rules" class="smpl">CRLF</a>
+         <div id="rfc.section.4.p.2"><pre class="inline prettyprint lang-ietf_abnf"><span id="rfc.iref.g.16"></span>  <a href="#status.line" class="smpl">status-line</a> = <a href="#http.version" class="smpl">HTTP-version</a> <a href="#core.rules" class="smpl">SP</a> <a href="#status.line" class="smpl">status-code</a> <a href="#core.rules" class="smpl">SP</a> [<a href="#status.line" class="smpl">reason-phrase</a>] <a href="#core.rules" class="smpl">CRLF</a>
 </pre></div>
          <div id="rfc.section.4.p.3">
             <p>Although the status-line grammar rule requires that each of the component elements
@@ -1351,7 +1350,12 @@ <h2 id="rfc.section.4"><a href="#rfc.section.4">4.</a>&nbsp;<a href="#status.lin
                (it might be discarded or overwritten by intermediaries, and it is not transmitted
                in other versions of HTTP).<a class="self" href="#rfc.section.4.p.7">¶</a></p>
          </div>
-         <div id="rfc.section.4.p.8"><pre class="inline prettyprint lang-ietf_abnf"><span id="rfc.iref.g.18"></span>  <a href="#status.line" class="smpl">reason-phrase</a>  = *( <a href="#core.rules" class="smpl">HTAB</a> / <a href="#core.rules" class="smpl">SP</a> / <a href="#core.rules" class="smpl">VCHAR</a> / <a href="#imported.rules" class="smpl">obs-text</a> )
+         <div id="rfc.section.4.p.8">
+            <p>Note that while the reason-phrase is optional, the preceding SP character is not.
+               In other words, absent a reason-phrase the status-line ends with a trailing SP, followed
+               by CRLF.<a class="self" href="#rfc.section.4.p.8">¶</a></p>
+         </div>
+         <div id="rfc.section.4.p.9"><pre class="inline prettyprint lang-ietf_abnf"><span id="rfc.iref.g.18"></span>  <a href="#status.line" class="smpl">reason-phrase</a>  = 1*( <a href="#core.rules" class="smpl">HTAB</a> / <a href="#core.rules" class="smpl">SP</a> / <a href="#core.rules" class="smpl">VCHAR</a> / <a href="#imported.rules" class="smpl">obs-text</a> )
 </pre></div>
       </section>
       <section id="header.fields">
@@ -2958,14 +2962,14 @@ <h2 id="rfc.section.A" class="np"><a href="#rfc.section.A">Appendix A.</a>&nbsp;
 <a href="#imported.rules" class="smpl">quoted-string</a> = &lt;quoted-string, see <a href="#Semantics" id="rfc.xref.Semantics.63"><cite title="HTTP Semantics">[Semantics]</cite></a>, <a href="draft-ietf-httpbis-semantics-latest.html#rfc.section.4.2.3">Section 4.2.3</a>&gt;
 
 <a href="#header.te" class="smpl">rank</a> = ( "0" [ "." *3DIGIT ] ) / ( "1" [ "." *3"0" ] )
-<a href="#status.line" class="smpl">reason-phrase</a> = *( HTAB / SP / VCHAR / obs-text )
+<a href="#status.line" class="smpl">reason-phrase</a> = 1*( HTAB / SP / VCHAR / obs-text )
 <a href="#request.line" class="smpl">request-line</a> = method SP request-target SP HTTP-version CRLF
 <a href="#request.target" class="smpl">request-target</a> = origin-form / absolute-form / authority-form /
  asterisk-form
 
 <a href="#message.format" class="smpl">start-line</a> = request-line / status-line
 <a href="#status.line" class="smpl">status-code</a> = 3DIGIT
-<a href="#status.line" class="smpl">status-line</a> = HTTP-version SP status-code SP reason-phrase CRLF
+<a href="#status.line" class="smpl">status-line</a> = HTTP-version SP status-code SP [ reason-phrase ] CRLF
 
 <a href="#header.te" class="smpl">t-codings</a> = "trailers" / ( transfer-coding [ t-ranking ] )
 <a href="#header.te" class="smpl">t-ranking</a> = OWS ";" OWS "q=" rank
@@ -3285,6 +3289,8 @@ <h3 id="rfc.section.D.6"><a href="#rfc.section.D.6">D.6.</a>&nbsp;<a href="#chan
                <ul>
                   <li>In <a href="#header.upgrade" id="rfc.xref.header.upgrade.2" title="Upgrade">Section&nbsp;9.8</a>, clarify that protocol-name is to be matched case-insensitively (&lt;<a href="https://github.com/httpwg/http-core/issues/8">https://github.com/httpwg/http-core/issues/8</a>&gt;)
                   </li>
+                  <li>In <a href="#status.line" title="Status Line">Section&nbsp;4</a>, add clarifications about empty reason phrases (&lt;<a href="https://github.com/httpwg/http-core/issues/197">https://github.com/httpwg/http-core/issues/197</a>&gt;)
+                  </li>
                </ul>
             </div>
          </section>
diff --git a/draft-ietf-httpbis-messaging-latest.xml b/draft-ietf-httpbis-messaging-latest.xml
index 2b311b04d..57938b9e8 100644
--- a/draft-ietf-httpbis-messaging-latest.xml
+++ b/draft-ietf-httpbis-messaging-latest.xml
@@ -717,11 +717,11 @@ https://www.example.org
 <t>
    The first line of a response message is the status-line, consisting
    of the protocol version, a space (SP), the status code, another space,
-   a possibly empty textual phrase describing the status code, and
+   an &OPTIONAL; textual phrase describing the status code, and
    ending with CRLF.
 </t>
 <sourcecode type="abnf7230"><iref primary="true" item="Grammar" subitem="status-line"/>
-  <x:ref>status-line</x:ref> = <x:ref>HTTP-version</x:ref> <x:ref>SP</x:ref> <x:ref>status-code</x:ref> <x:ref>SP</x:ref> <x:ref>reason-phrase</x:ref> <x:ref>CRLF</x:ref>
+  <x:ref>status-line</x:ref> = <x:ref>HTTP-version</x:ref> <x:ref>SP</x:ref> <x:ref>status-code</x:ref> <x:ref>SP</x:ref> [<x:ref>reason-phrase</x:ref>] <x:ref>CRLF</x:ref>
 </sourcecode>
 <t>
    Although the status-line grammar rule requires that each of the component
@@ -759,8 +759,13 @@ https://www.example.org
    reliable channel for information (it might be discarded or overwritten by
    intermediaries, and it is not transmitted in other versions of HTTP).
 </t>
+<t>
+   Note that while the reason-phrase is optional, the preceding SP character
+   is not. In other words, absent a reason-phrase the status-line ends
+   with a trailing SP, followed by CRLF.
+</t>
 <sourcecode type="abnf7230"><iref primary="true" item="Grammar" subitem="reason-phrase"/>
-  <x:ref>reason-phrase</x:ref>  = *( <x:ref>HTAB</x:ref> / <x:ref>SP</x:ref> / <x:ref>VCHAR</x:ref> / <x:ref>obs-text</x:ref> )
+  <x:ref>reason-phrase</x:ref>  = 1*( <x:ref>HTAB</x:ref> / <x:ref>SP</x:ref> / <x:ref>VCHAR</x:ref> / <x:ref>obs-text</x:ref> )
 </sourcecode>
 </section>
 
@@ -3030,14 +3035,14 @@ Upgrade: HTTP/2.0
 <x:ref>quoted-string</x:ref> = &lt;quoted-string, see <xref target="Semantics" x:fmt="," x:sec="4.2.3"/>&gt;
 
 <x:ref>rank</x:ref> = ( "0" [ "." *3DIGIT ] ) / ( "1" [ "." *3"0" ] )
-<x:ref>reason-phrase</x:ref> = *( HTAB / SP / VCHAR / obs-text )
+<x:ref>reason-phrase</x:ref> = 1*( HTAB / SP / VCHAR / obs-text )
 <x:ref>request-line</x:ref> = method SP request-target SP HTTP-version CRLF
 <x:ref>request-target</x:ref> = origin-form / absolute-form / authority-form /
  asterisk-form
 
 <x:ref>start-line</x:ref> = request-line / status-line
 <x:ref>status-code</x:ref> = 3DIGIT
-<x:ref>status-line</x:ref> = HTTP-version SP status-code SP reason-phrase CRLF
+<x:ref>status-line</x:ref> = HTTP-version SP status-code SP [ reason-phrase ] CRLF
 
 <x:ref>t-codings</x:ref> = "trailers" / ( transfer-coding [ t-ranking ] )
 <x:ref>t-ranking</x:ref> = OWS ";" OWS "q=" rank
@@ -3379,6 +3384,7 @@ Upgrade: HTTP/2.0
 <section title="Since draft-ietf-httpbis-messaging-04" anchor="changes.since.04">
 <ul>
   <li>In <xref target="header.upgrade"/>, clarify that protocol-name is to be matched case-insensitively (<eref target="https://github.com/httpwg/http-core/issues/8"/>)</li>
+  <li>In <xref target="status.line"/>, add clarifications about empty reason phrases (<eref target="https://github.com/httpwg/http-core/issues/197"/>)</li>
 </ul>
 </section>
 
diff --git a/httpbis.abnf b/httpbis.abnf
index 305def644..667ea1975 100644
--- a/httpbis.abnf
+++ b/httpbis.abnf
@@ -187,7 +187,7 @@ quoted-string = DQUOTE *( qdtext / quoted-pair ) DQUOTE
 qvalue = ( "0" [ "." *3DIGIT ] ) / ( "1" [ "." *3"0" ] )
 range-unit = bytes-unit / other-range-unit
 rank = ( "0" [ "." *3DIGIT ] ) / ( "1" [ "." *3"0" ] )
-reason-phrase = *( HTAB / SP / VCHAR / obs-text )
+reason-phrase = 1*( HTAB / SP / VCHAR / obs-text )
 received-by = ( uri-host [ ":" port ] ) / pseudonym
 received-protocol = [ protocol-name "/" ] protocol-version
 relative-part = <relative-part, see [RFC3986], Section 4.2>
@@ -198,7 +198,7 @@ second = 2DIGIT
 segment = <segment, see [RFC3986], Section 3.3>
 start-line = request-line / status-line
 status-code = 3DIGIT
-status-line = HTTP-version SP status-code SP reason-phrase CRLF
+status-line = HTTP-version SP status-code SP [ reason-phrase ] CRLF
 subtype = token
 suffix-byte-range-spec = "-" suffix-length
 suffix-length = 1*DIGIT