diff --git a/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Denied.java b/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Denied.java
index ccb7f7185..bf9e8fe2e 100644
--- a/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Denied.java
+++ b/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Denied.java
@@ -63,6 +63,10 @@ import java.util.UUID;
             } else {
                 uuid = UUIDHandler.getUUID(args[1]);
             }
+            if (uuid == null) {
+                PlayerFunctions.sendMessage(plr, C.INVALID_PLAYER, args[1]);
+                return false;
+            }
             if (!plot.denied.contains(uuid)) {
                 if (plot.owner == uuid) {
                     PlayerFunctions.sendMessage(plr, C.ALREADY_OWNER);
diff --git a/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Helpers.java b/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Helpers.java
index 2a298b3dd..32503280c 100644
--- a/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Helpers.java
+++ b/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Helpers.java
@@ -62,6 +62,10 @@ import java.util.UUID;
             } else {
                 uuid = UUIDHandler.getUUID(args[1]);
             }
+            if (uuid == null) {
+                PlayerFunctions.sendMessage(plr, C.INVALID_PLAYER, args[1]);
+                return false;
+            }
             if (!plot.helpers.contains(uuid)) {
                 if (plot.owner == uuid) {
                     PlayerFunctions.sendMessage(plr, C.ALREADY_OWNER);
diff --git a/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Info.java b/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Info.java
index 2d3012df3..3db811c69 100644
--- a/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Info.java
+++ b/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Info.java
@@ -219,7 +219,7 @@ import java.util.UUID;
 
     private String getPlayerName(final UUID uuid) {
         if (uuid == null) {
-            return uuid.toString();
+            return "unknown";
         }
         if (uuid.equals(DBFunc.everyone) || uuid.toString().equalsIgnoreCase(DBFunc.everyone.toString())) {
             return "everyone";
diff --git a/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/SetOwner.java b/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/SetOwner.java
index ff6ddc91a..b790d5e54 100644
--- a/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/SetOwner.java
+++ b/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/SetOwner.java
@@ -71,7 +71,15 @@ import java.util.UUID;
 
         for (final PlotId id : plots) {
             final Plot current = PlotMain.getPlots(world).get(id);
-            current.owner = getUUID(args[0]);
+            
+            UUID uuid = getUUID(args[0]);
+            
+            if (uuid == null) {
+                PlayerFunctions.sendMessage(plr, C.INVALID_PLAYER, args[1]);
+                return false;
+            }
+            
+            current.owner = uuid;
             PlotMain.updatePlot(current);
             DBFunc.setOwner(current, current.owner);
 
diff --git a/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Trusted.java b/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Trusted.java
index e221ebe9c..b07c697eb 100644
--- a/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Trusted.java
+++ b/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/Trusted.java
@@ -63,6 +63,10 @@ import java.util.UUID;
             } else {
                 uuid = UUIDHandler.getUUID(args[1]);
             }
+            if (uuid == null) {
+                PlayerFunctions.sendMessage(plr, C.INVALID_PLAYER, args[1]);
+                return false;
+            }
             if (!plot.trusted.contains(uuid)) {
                 if (plot.owner == uuid) {
                     PlayerFunctions.sendMessage(plr, C.ALREADY_OWNER);
diff --git a/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/list.java b/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/list.java
index 33fb952ea..7e0e4dd06 100644
--- a/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/list.java
+++ b/PlotSquared/src/main/java/com/intellectualcrafters/plot/commands/list.java
@@ -51,7 +51,11 @@ public class list extends SubCommand {
          * String name = Bukkit.getOfflinePlayer(id).getName(); if (name ==
          * null) { return "none"; } return name;
          */
-        return UUIDHandler.getName(id);
+        String name = UUIDHandler.getName(id);
+        if (name == null) {
+            return "unknown";
+        }
+        return name;
     }
 
     @Override