diff --git a/man/ostree-diff.xml b/man/ostree-diff.xml
index 10658cf2..0b7ac892 100644
--- a/man/ostree-diff.xml
+++ b/man/ostree-diff.xml
@@ -51,7 +51,7 @@ Boston, MA 02111-1307, USA.
 
     <refsynopsisdiv>
             <cmdsynopsis>
-                <command>ostree diff</command> <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="req">REV</arg> <arg choice="req">TARGETDIR</arg>
+              <command>ostree diff</command> <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="req">REV_OR_DIR</arg> <arg choice="req">REV_OR_DIR</arg>
             </cmdsynopsis>
     </refsynopsisdiv>
 
@@ -59,7 +59,7 @@ Boston, MA 02111-1307, USA.
         <title>Description</title>
 
         <para>
-            Compare directory TARGETDIR against revision REV.  Shows files and directories modified, added, and deleted.  If there is a file in TARGETDIR not in REV, it will show with an "A" for "added".  If a file in REV is not in TARGETDIR, it shows "D" for "deleted".  "M" for "modified" will also show.
+          Compare a directory or revision against another directory or revision. If REV_OR_DIR starts with `/` or `./`, it is interpreted as a directory, otherwise a revision. Shows files and directories modified, added, and deleted.  If there is a file in the second REV_OR_DIR not in the first, it will show with an "A" for "added".  If a file in the first REV_OR_DIR is not in the second, it shows "D" for "deleted".  "M" for "modified" will also show.
         </para>
     </refsect1>
 
diff --git a/src/ostree/ot-builtin-diff.c b/src/ostree/ot-builtin-diff.c
index 1f0488de..82a533d5 100644
--- a/src/ostree/ot-builtin-diff.c
+++ b/src/ostree/ot-builtin-diff.c
@@ -142,7 +142,7 @@ ostree_builtin_diff (int argc, char **argv, OstreeCommandInvocation *invocation,
   g_autoptr(GPtrArray) removed = NULL;
   g_autoptr(GPtrArray) added = NULL;
 
-  context = g_option_context_new ("REV TARGETDIR");
+  context = g_option_context_new ("REV_OR_DIR REV_OR_DIR");
 
   if (!ostree_option_context_parse (context, options, &argc, &argv, invocation, &repo, cancellable, error))
     goto out;