diff --git a/core/src/avm2/activation.rs b/core/src/avm2/activation.rs
index d2153323a..8cadbc083 100644
--- a/core/src/avm2/activation.rs
+++ b/core/src/avm2/activation.rs
@@ -1405,9 +1405,9 @@ impl<'a, 'gc, 'gc_context> Activation<'a, 'gc, 'gc_context> {
             (multiname, object)
         };
 
-        self.context
-            .avm2
-            .push(object.delete_property(self.context.gc_context, &multiname)?);
+        let did_delete = object.delete_property(self, &multiname)?;
+
+        self.context.avm2.push(did_delete);
 
         Ok(FrameControl::Continue)
     }
diff --git a/core/src/avm2/object.rs b/core/src/avm2/object.rs
index d325b764c..2ed1bc206 100644
--- a/core/src/avm2/object.rs
+++ b/core/src/avm2/object.rs
@@ -687,22 +687,36 @@ pub trait TObject<'gc>: 'gc + Collect + Debug + Into<Object<'gc>> + Clone + Copy
         Ok(base.delete_property(name))
     }
 
+    /// Delete a property that does not exist.
+    ///
+    /// By default, undefined property deletion succeeds for dynamic classes,
+    /// and fails for sealed ones. Objects that have particular alternative
+    /// behavior for undefined values may substitute their own implementation
+    /// here without disturbing the rest of `deleteproperty`'s implementation.
+    fn delete_property_undef(
+        &self,
+        _activation: &mut Activation<'_, 'gc, '_>,
+        _multiname: &Multiname<'gc>,
+    ) -> Result<bool, Error> {
+        // Unknown properties on a dynamic class delete successfully.
+        return Ok(!self
+            .instance_of_class_definition()
+            .map(|c| c.read().is_sealed())
+            .unwrap_or(false));
+    }
+
     /// Delete a named property from the object.
     ///
     /// Returns false if the property cannot be deleted.
     fn delete_property(
         &self,
-        gc_context: MutationContext<'gc, '_>,
+        activation: &mut Activation<'_, 'gc, '_>,
         multiname: &Multiname<'gc>,
     ) -> Result<bool, Error> {
         let name = self.resolve_multiname(multiname)?;
 
         if name.is_none() {
-            // Unknown properties on a dynamic class delete successfully.
-            return Ok(!self
-                .instance_of_class_definition()
-                .map(|c| c.read().is_sealed())
-                .unwrap_or(false));
+            return self.delete_property_undef(activation, multiname);
         }
 
         //At this point, the name should be known.
@@ -732,7 +746,7 @@ pub trait TObject<'gc>: 'gc + Collect + Debug + Into<Object<'gc>> + Clone + Copy
             }
         }
 
-        self.delete_property_local(gc_context, &name)
+        self.delete_property_local(activation.context.gc_context, &name)
     }
 
     /// Retrieve the `__proto__` of a given object.
diff --git a/core/src/avm2/object/proxy_object.rs b/core/src/avm2/object/proxy_object.rs
index 4490cb19e..011513efa 100644
--- a/core/src/avm2/object/proxy_object.rs
+++ b/core/src/avm2/object/proxy_object.rs
@@ -172,4 +172,39 @@ impl<'gc> TObject<'gc> for ProxyObject<'gc> {
         )
         .into())
     }
+
+    fn delete_property_undef(
+        &self,
+        activation: &mut Activation<'_, 'gc, '_>,
+        multiname: &Multiname<'gc>,
+    ) -> Result<bool, Error> {
+        for namespace in multiname.namespace_set() {
+            if let Some(local_name) = multiname.local_name() {
+                if namespace.is_any() || namespace.is_public() || namespace.is_namespace() {
+                    let qname = QNameObject::from_qname(
+                        activation,
+                        QName::new(namespace.clone(), local_name),
+                    )?;
+
+                    return Ok(self
+                        .call_property(
+                            &QName::new(
+                                Namespace::Namespace(NS_FLASH_PROXY.into()),
+                                "deleteProperty",
+                            )
+                            .into(),
+                            &[qname.into()],
+                            activation,
+                        )?
+                        .coerce_to_boolean());
+                }
+            }
+        }
+
+        // Unknown properties on a dynamic class delete successfully.
+        return Ok(!self
+            .instance_of_class_definition()
+            .map(|c| c.read().is_sealed())
+            .unwrap_or(false));
+    }
 }
diff --git a/tests/tests/swfs/avm2/proxy_deleteproperty/Test.as b/tests/tests/swfs/avm2/proxy_deleteproperty/Test.as
index 4f5a33690..8d5dbcb3c 100644
--- a/tests/tests/swfs/avm2/proxy_deleteproperty/Test.as
+++ b/tests/tests/swfs/avm2/proxy_deleteproperty/Test.as
@@ -17,6 +17,11 @@ dynamic class TestProxy extends Proxy {
 			
 			trace("///name.uri");
 			trace(name.uri);
+			
+			if (name.localName === "crazy_return") {
+				trace("///returning non-bool value");
+				return "This isn't a bool at all";
+			}
 		} else if (name is String) {
 			trace("///type of name is String");
 		} else {
@@ -71,4 +76,7 @@ trace("///delete p.proxy_var");
 trace(delete p.proxy_var);
 
 trace("///delete p.proxy_fn");
-trace(delete p.proxy_fn);
\ No newline at end of file
+trace(delete p.proxy_fn);
+
+trace("///delete p.crazy_return");
+trace(delete p.crazy_return);
\ No newline at end of file
diff --git a/tests/tests/swfs/avm2/proxy_deleteproperty/output.txt b/tests/tests/swfs/avm2/proxy_deleteproperty/output.txt
index 4586c7927..e3037eb42 100644
--- a/tests/tests/swfs/avm2/proxy_deleteproperty/output.txt
+++ b/tests/tests/swfs/avm2/proxy_deleteproperty/output.txt
@@ -57,3 +57,12 @@ proxy_fn
 ///name.uri
 
 true
+///delete p.crazy_return
+///attempted to delete property: crazy_return
+///type of name is QName
+///name.localName
+crazy_return
+///name.uri
+
+///returning non-bool value
+true
diff --git a/tests/tests/swfs/avm2/proxy_deleteproperty/test.swf b/tests/tests/swfs/avm2/proxy_deleteproperty/test.swf
index da98fc771..ecbcafb78 100644
Binary files a/tests/tests/swfs/avm2/proxy_deleteproperty/test.swf and b/tests/tests/swfs/avm2/proxy_deleteproperty/test.swf differ