diff --git a/build/build.xml b/build/build.xml
index 97abc2e06..3ba471098 100644
--- a/build/build.xml
+++ b/build/build.xml
@@ -559,6 +559,9 @@
       <!-- avoid conflicts with JNA DLLs already in the path -->
       <option value="-Djna.nosys=true" />
 
+      <!-- deal with jokers who install JOGL, ANTLR, etc system-wide -->
+      <option value="-Djava.ext.dirs=lib/ext" />
+
       <option value="-Dapple.laf.useScreenMenuBar=true" />
       <option value="-Dcom.apple.macos.use-file-dialog-packages=true" />
       <option value="-Dcom.apple.macos.useScreenMenuBar=true" />
diff --git a/build/linux/processing b/build/linux/processing
index e7982b0e4..9a35f59fe 100755
--- a/build/linux/processing
+++ b/build/linux/processing
@@ -104,7 +104,7 @@ cmd_name='processing-java'
 
 if [ $current_name = $cmd_name ]
 then
-    java -Djna.nosys=true -Xmx256m processing.mode.java.Commander "$@"
+    java -Djna.nosys=true -Djava.ext.dirs=lib/ext -Xmx256m processing.mode.java.Commander "$@"
     exit $?
 else
   # Start Processing in the same directory as this script
@@ -115,5 +115,5 @@ else
   fi
   cd "$APPDIR"
 
-  java -splash:lib/about-1x.png -Djna.nosys=true -Xmx256m processing.app.Base "$SKETCH" &
+  java -splash:lib/about-1x.png -Djna.nosys=true -Djava.ext.dirs=lib/ext -Xmx256m processing.app.Base "$SKETCH" &
 fi
diff --git a/build/windows/config-cmd.xml b/build/windows/config-cmd.xml
index 177bc8b4b..010ab775e 100644
--- a/build/windows/config-cmd.xml
+++ b/build/windows/config-cmd.xml
@@ -29,6 +29,8 @@
 
   <jre>
     <path>java</path>
+    <!-- Deal with jokers who install JOGL, ANTLR, etc system-wide -->
+    <opt>-Djava.ext.dirs=lib/ext</opt>
     <!-- Prevent a user-installed JNA from conflicting with our version.
          https://github.com/processing/processing/issues/2239 -->
     <opt>-Djna.nosys=true</opt>
diff --git a/build/windows/config.xml b/build/windows/config.xml
index 7eedde6d2..a3b83a0d0 100644
--- a/build/windows/config.xml
+++ b/build/windows/config.xml
@@ -26,6 +26,8 @@
   </classPath>
   <jre>
     <path>java</path>
+    <!-- Deal with jokers who install JOGL, ANTLR, etc system-wide -->
+    <opt>-Djava.ext.dirs=lib/ext</opt>
     <!-- https://github.com/processing/processing/issues/2239 -->
     <opt>-Djna.nosys=true</opt>
     <!-- Because nosys is set to true, the DLL in the current working 
diff --git a/todo.txt b/todo.txt
index 0ad76b34d..06f99c7c6 100644
--- a/todo.txt
+++ b/todo.txt
@@ -1,15 +1,19 @@
 0252 (3.2)
-_ Move general PDE code out of JavaMode and into general base classes
-_   https://github.com/processing/processing/issues/4606
+X Move general PDE code out of JavaMode and into general base classes
+X   https://github.com/processing/processing/issues/4606
 X change PdeInputHandler constructor
-_   check whether this breaks other Modes before releasing
+X   check whether this breaks other Modes before releasing
+X   added extra constructor to keep things working
+X Processing .jar files in CLASSPATH can cause startup crash
+X   https://github.com/processing/processing/issues/4128
+X Remove java.ext.dirs on startup to avoid conflicts and startup errors
+X   https://github.com/processing/processing/issues/4608
+
 _ modify line number color when no lines extend that far?
 _   https://github.com/processing/processing/pull/4560
 _ text gutter doesn't seem to be hidpi 
 X   or is it b/c screen not quite 2x? (nope)
 _ swap out the fonts?
-_ Processing .jar files in CLASSPATH can cause startup crash
-_   https://github.com/processing/processing/issues/4128
 
 _ Help Menu disabled on OS X
 _   https://github.com/processing/processing/issues/43503#issuecomment-237715947