diff --git a/man/journald.conf.xml b/man/journald.conf.xml
index 109ca960fb..4464fe53ad 100644
--- a/man/journald.conf.xml
+++ b/man/journald.conf.xml
@@ -211,8 +211,9 @@
         and use the smaller of the two values.</para>
 
         <para>The first pair defaults to 10% and the second to 15% of
-        the size of the respective file system. If the file system is
-        nearly full and either <varname>SystemKeepFree=</varname> or
+        the size of the respective file system, but each value is
+        capped to 4G. If the file system is nearly full and either
+        <varname>SystemKeepFree=</varname> or
         <varname>RuntimeKeepFree=</varname> are violated when
         systemd-journald is started, the limit will be raised to the
         percentage that is actually free. This means that if there was