diff --git a/src/Func.cc b/src/Func.cc
index 319868395e..f24154d1a5 100644
--- a/src/Func.cc
+++ b/src/Func.cc
@@ -587,6 +587,11 @@ bool ScriptFunc::StrengthenClosureReference(Frame* f)
 	return true;
 	}
 
+bool ScriptFunc::CopySemantics() const
+	{
+	return type->GetCaptures().has_value();
+	}
+
 void ScriptFunc::SetClosureFrame(Frame* f)
 	{
 	if ( closure )
diff --git a/src/Func.h b/src/Func.h
index db15fde849..9729fbca1d 100644
--- a/src/Func.h
+++ b/src/Func.h
@@ -145,7 +145,7 @@ protected:
 
 namespace detail {
 
-class ScriptFunc final : public Func {
+class ScriptFunc : public Func {
 public:
 	ScriptFunc(const IDPtr& id, StmtPtr body,
 	        const std::vector<IDPtr>& inits,
@@ -210,12 +210,17 @@ public:
 	 */
 	bool StrengthenClosureReference(Frame* f);
 
+	/**
+	 * Whether the function's closure uses copy semantics.
+	 */
+	virtual bool CopySemantics() const;
+
 	/**
 	 * Serializes this function's closure or capture frame.
 	 *
 	 * @return a serialized version of the function's closure/capture frame.
 	 */
-	broker::expected<broker::data> SerializeClosure() const;
+	virtual broker::expected<broker::data> SerializeClosure() const;
 
 	/**
 	 * Sets the captures frame to one built from *data*.
@@ -257,6 +262,7 @@ public:
 
 protected:
 	ScriptFunc() : Func(SCRIPT_FUNC)	{}
+
 	StmtPtr AddInits(
 		StmtPtr body,
 		const std::vector<IDPtr>& inits);
@@ -280,7 +286,7 @@ protected:
 	 *
 	 * @param f  the frame holding the values of capture variables
 	 */
-	void SetCaptures(Frame* f);
+	virtual void SetCaptures(Frame* f);
 
 private:
 	size_t frame_size;
diff --git a/src/broker/Data.cc b/src/broker/Data.cc
index 2af93460bd..db372de6fe 100644
--- a/src/broker/Data.cc
+++ b/src/broker/Data.cc
@@ -392,6 +392,17 @@ struct val_converter {
 
 			if ( a.size() == 2 ) // we have a closure/capture frame
 				{
+				// Note, seems if we already have a separate
+				// instance of the same lambda, then unless
+				// we use a cloned value, we'll step on that
+				// one's captures, too.  This is because
+				// the capture mapping lives with the Func
+				// object rather than the FuncVal.  However,
+				// we can't readily Clone() here because
+				// rval is const (and, grrr, Clone() is not).
+				// -VP
+				// rval = rval->Clone();
+
 				auto frame = broker::get_if<broker::vector>(a[1]);
 				if ( ! frame )
 					return nullptr;
@@ -400,9 +411,7 @@ struct val_converter {
 				if ( ! b )
 					return nullptr;
 
-				auto copy_semantics = b->GetType()->GetCaptures().has_value();
-
-				if ( copy_semantics )
+				if ( b->CopySemantics() )
 					{
 					if ( ! b->DeserializeCaptures(*frame) )
 						return nullptr;