diff --git a/src/main/java/dev/jlibghostty/Terminal.java b/src/main/java/dev/jlibghostty/Terminal.java
index d19b9cc..1ed3f6e 100644
--- a/src/main/java/dev/jlibghostty/Terminal.java
+++ b/src/main/java/dev/jlibghostty/Terminal.java
@@ -11,8 +11,9 @@ import java.util.concurrent.atomic.AtomicBoolean;
 public final class Terminal implements AutoCloseable {
     private final GhosttyLibrary library;
     private final MemorySegment handle;
-    private final Arena callbackArena = Arena.ofShared();
     private final AtomicBoolean closed = new AtomicBoolean();
+    private Arena ptyWriterArena;
+    private Arena deviceAttributesArena;
     private MemorySegment ptyWriterStub = MemorySegment.NULL;
     private MemorySegment deviceAttributesStub = MemorySegment.NULL;
     private PtyWriter ptyWriter;
@@ -40,31 +41,51 @@ public final class Terminal implements AutoCloseable {
     public void setPtyWriter(PtyWriter writer) {
         ensureOpen();
         ptyWriter = writer;
+
+        // Each upcall stub lives in its own arena so that reassigning (or clearing) the
+        // writer can free the previous stub. The native pointer is repointed before the old
+        // arena is closed, so native never holds a dangling stub.
+        Arena previous = ptyWriterArena;
         if (writer == null) {
             ptyWriterStub = MemorySegment.NULL;
+            ptyWriterArena = null;
             library.terminalSetPointer(handle, GhosttyLibrary.TERMINAL_OPT_WRITE_PTY, MemorySegment.NULL);
-            return;
+        } else {
+            Arena arena = Arena.ofShared();
+            ptyWriterStub = library.upcallPtyWriter(writer, arena);
+            ptyWriterArena = arena;
+            library.terminalSetPointer(handle, GhosttyLibrary.TERMINAL_OPT_WRITE_PTY, ptyWriterStub);
         }
 
-        ptyWriterStub = library.upcallPtyWriter(writer, callbackArena);
-        library.terminalSetPointer(handle, GhosttyLibrary.TERMINAL_OPT_WRITE_PTY, ptyWriterStub);
+        if (previous != null) {
+            previous.close();
+        }
     }
 
     public void setDeviceAttributesProvider(DeviceAttributesProvider provider) {
         ensureOpen();
         deviceAttributesProvider = provider;
+
+        // See setPtyWriter: a per-stub arena lets reassignment free the previous stub.
+        Arena previous = deviceAttributesArena;
         if (provider == null) {
             deviceAttributesStub = MemorySegment.NULL;
+            deviceAttributesArena = null;
             library.terminalSetPointer(handle, GhosttyLibrary.TERMINAL_OPT_DEVICE_ATTRIBUTES, MemorySegment.NULL);
-            return;
+        } else {
+            Arena arena = Arena.ofShared();
+            deviceAttributesStub = library.upcallDeviceAttributesProvider(provider, arena);
+            deviceAttributesArena = arena;
+            library.terminalSetPointer(
+                handle,
+                GhosttyLibrary.TERMINAL_OPT_DEVICE_ATTRIBUTES,
+                deviceAttributesStub
+            );
         }
 
-        deviceAttributesStub = library.upcallDeviceAttributesProvider(provider, callbackArena);
-        library.terminalSetPointer(
-            handle,
-            GhosttyLibrary.TERMINAL_OPT_DEVICE_ATTRIBUTES,
-            deviceAttributesStub
-        );
+        if (previous != null) {
+            previous.close();
+        }
     }
 
     public String text() {
@@ -156,7 +177,14 @@ public final class Terminal implements AutoCloseable {
     public void close() {
         if (closed.compareAndSet(false, true)) {
             library.terminalFree(handle);
-            callbackArena.close();
+            if (ptyWriterArena != null) {
+                ptyWriterArena.close();
+                ptyWriterArena = null;
+            }
+            if (deviceAttributesArena != null) {
+                deviceAttributesArena.close();
+                deviceAttributesArena = null;
+            }
         }
     }