diff --git a/src/script_opt/ScriptOpt.cc b/src/script_opt/ScriptOpt.cc
index 0ac62f4e68..39ab8adb6f 100644
--- a/src/script_opt/ScriptOpt.cc
+++ b/src/script_opt/ScriptOpt.cc
@@ -130,13 +130,19 @@ void optimize_func(ScriptFunc* f, std::shared_ptr<ProfileFunc> pf,
 
 	rc->SetDefSetsMgr(reduced_rds.GetDefSetsMgr());
 
-	auto ud = std::make_unique<UseDefs>(body, rc);
+	auto ud = std::make_shared<UseDefs>(body, rc);
 	ud->Analyze();
 
 	if ( analysis_options.dump_uds )
 		ud->Dump();
 
-	ud->RemoveUnused();
+	new_body = ud->RemoveUnused();
+
+	if ( new_body != body )
+		{
+		f->ReplaceBody(body, new_body);
+		body = new_body;
+		}
 
 	int new_frame_size =
 		scope->Length() + rc->NumTemps() + rc->NumNewLocals();
diff --git a/src/script_opt/UseDefs.cc b/src/script_opt/UseDefs.cc
index f8476e5d68..c26ad73f09 100644
--- a/src/script_opt/UseDefs.cc
+++ b/src/script_opt/UseDefs.cc
@@ -37,7 +37,7 @@ void UseDefs::Analyze()
 	(void) PropagateUDs(body, nullptr, nullptr, false);
 	}
 
-void UseDefs::RemoveUnused()
+StmtPtr UseDefs::RemoveUnused()
 	{
 	int iter = 0;
 	while ( RemoveUnused(++iter) )
@@ -48,6 +48,8 @@ void UseDefs::RemoveUnused()
 		if ( reporter->Errors() > 0 )
 			break;
 		}
+
+	return body;
 	}
 
 void UseDefs::Dump()
diff --git a/src/script_opt/UseDefs.h b/src/script_opt/UseDefs.h
index a00b42e0cf..2d61fb4f20 100644
--- a/src/script_opt/UseDefs.h
+++ b/src/script_opt/UseDefs.h
@@ -57,14 +57,18 @@ public:
 	// True if we've computed use-defs for the given statement.
 	bool HasUsage(const Stmt* s) const
 		{ return use_defs_map.find(s) != use_defs_map.end(); }
+	bool HasUsage(const StmtPtr& s) const
+		{ return HasUsage(s.get()); }
 
 	// Returns the use-defs for the given statement.
 	UDs GetUsage(const Stmt* s) const	{ return FindUsage(s); }
+	UDs GetUsage(const StmtPtr& s) const	{ return FindUsage(s.get()); }
 
 	// Removes assignments corresponding to unused temporaries.
 	// In the process, reports on locals that are assigned
-	// but never used.
-	void RemoveUnused();
+	// but never used.  Returns the body, which may have been
+	// changed if the original first statement has been pruned.
+	StmtPtr RemoveUnused();
 
 	void Dump();