diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9f825709..afae8d33 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## ??? (Not Released Yet)
+
+* Fix mod_muc_slow_mode: add min value for slow_mode_duration field.
+
 ## 8.3.1
 
 * Fix: video owner must be room owner, not only admin. Otherwise they can't edit room parameters (including slow mode settings).
diff --git a/prosody-modules/mod_muc_slow_mode/mod_muc_slow_mode.lua b/prosody-modules/mod_muc_slow_mode/mod_muc_slow_mode.lua
index 27ad0c11..8b4febfc 100644
--- a/prosody-modules/mod_muc_slow_mode/mod_muc_slow_mode.lua
+++ b/prosody-modules/mod_muc_slow_mode/mod_muc_slow_mode.lua
@@ -66,6 +66,7 @@ local function add_form_option(event)
     name = "muc#roomconfig_slow_mode_duration";
     type = "text-single";
     datatype = "xs:integer";
+    range_min = 0;
     label = "Slow Mode (0=disabled, any positive integer= users can send a message every X seconds.)";
     -- desc = "";
     value = get_slow_mode_duration(event.room);