diff --git a/modules/commands/cs_mode.cpp b/modules/commands/cs_mode.cpp
index d5c356fa4..8a30f102c 100644
--- a/modules/commands/cs_mode.cpp
+++ b/modules/commands/cs_mode.cpp
@@ -958,16 +958,40 @@ class CSMode : public Module
 			for (unsigned i = 0; i < mlock.length(); ++i)
 			{
 				if (mlock[i] == '+')
-					add = true;
-				else if (mlock[i] == '-')
-					add = false;
-				else
 				{
-					ChannelMode *cm = ModeManager::FindChannelModeByChar(mlock[i]);
-					Anope::string param;
-					if (cm && (cm->type == MODE_REGULAR || sep.GetToken(param)))
-						ml->SetMLock(cm, add, param);
+					add = true;
+					continue;
 				}
+
+				if (mlock[i] == '-')
+				{
+					add = false;
+					continue;
+				}
+
+				ChannelMode *cm = ModeManager::FindChannelModeByChar(mlock[i]);
+				if (!cm)
+					continue;
+
+				Anope::string param;
+				if (cm->type == MODE_PARAM)
+				{
+					ChannelModeParam *cmp = anope_dynamic_static_cast<ChannelModeParam *>(cm);
+					if (add || !cmp->minus_no_arg)
+					{
+						sep.GetToken(param);
+						if (param.empty() || !cmp->IsValid(param))
+							continue;
+					}
+				}
+				else if (cm->type != MODE_REGULAR)
+				{
+					sep.GetToken(param);
+					if (param.empty())
+						continue;
+				}
+
+				ml->SetMLock(cm, add, param);
 			}
 		}
 		ml->Check();