diff --git a/wpilibc/wpilibC++Devices/src/Preferences.cpp b/wpilibc/wpilibC++Devices/src/Preferences.cpp
index 5ac0c5ee7f..70985bb2a7 100644
--- a/wpilibc/wpilibC++Devices/src/Preferences.cpp
+++ b/wpilibc/wpilibC++Devices/src/Preferences.cpp
@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) FIRST 2011. All Rights Reserved.							  */
+/* Copyright (c) FIRST 2011. All Rights Reserved.                             */
 /* Open Source Software - may be modified and shared by FRC teams. The code   */
 /* must be accompanied by the FIRST BSD license file in $(WIND_BASE)/WPILib.  */
 /*----------------------------------------------------------------------------*/
@@ -564,18 +564,20 @@ void Preferences::WriteTaskRun()
 }
 
 static bool isKeyAcceptable(const std::string& value) {
-    for (unsigned int i = 0; i < value.length(); i++) {
-        char letter = value.at(i);
-        switch (letter) {
-            case '=':
-            case '\n':
-            case '\r':
-            case ' ':
-            case '\t':
-            	return false;
-        }
-    }
-    return true;
+	for (unsigned int i = 0; i < value.length(); i++) {
+		char letter = value.at(i);
+		switch (letter) {
+		case '=':
+		case '\n':
+		case '\r':
+		case ' ':
+		case '\t':
+		case '[':
+		case ']':
+			return false;
+		}
+	}
+	return true;
 }
 void Preferences::ValueChanged(ITable* table, const std::string& key, EntryValue value, bool isNew)
 {
diff --git a/wpilibj/wpilibJavaDevices/src/main/java/edu/wpi/first/wpilibj/Preferences.java b/wpilibj/wpilibJavaDevices/src/main/java/edu/wpi/first/wpilibj/Preferences.java
index 4c615eb7e7..544da698a1 100644
--- a/wpilibj/wpilibJavaDevices/src/main/java/edu/wpi/first/wpilibj/Preferences.java
+++ b/wpilibj/wpilibJavaDevices/src/main/java/edu/wpi/first/wpilibj/Preferences.java
@@ -503,7 +503,7 @@ public class Preferences {
                 file.createNewFile();
 
                 output = new FileOutputStream(file);
-				
+
 				output.write("[Preferences]\n".getBytes());
 
                 for (int i = 0; i < keys.size(); i++) {
@@ -803,6 +803,8 @@ public class Preferences {
                 case '\r':
                 case ' ':
                 case '\t':
+                case '[':
+                case ']':
                     throw new ImproperPreferenceKeyException(value, letter);
                 }
             }
@@ -813,7 +815,7 @@ public class Preferences {
          * preference table.
          *
          * @param value
-         * @return
+         * @return true if the given string is ok to use in the preference table
          */
         public static boolean isAcceptable(String value) {
             for (int i = 0; i < value.length(); i++) {
@@ -824,6 +826,8 @@ public class Preferences {
                 case '\r':
                 case ' ':
                 case '\t':
+                case '[':
+                case ']':
                     return false;
                 }
             }