diff --git a/src/PacketFilter.cc b/src/PacketFilter.cc
index c89c59a39a..f506d1778e 100644
--- a/src/PacketFilter.cc
+++ b/src/PacketFilter.cc
@@ -1,11 +1,25 @@
 #include "PacketFilter.h"
 
+void PacketFilter::DeleteFilter(void* data)
+	{
+	auto f = static_cast<Filter*>(data);
+	delete f;
+	}
+
+PacketFilter::PacketFilter(bool arg_default)
+	{
+	default_match = arg_default;
+	src_filter.SetDeleteFunction(PacketFilter::DeleteFilter);
+	dst_filter.SetDeleteFunction(PacketFilter::DeleteFilter);
+	}
+
 void PacketFilter::AddSrc(const IPAddr& src, uint32_t tcp_flags, double probability)
 	{
 	Filter* f = new Filter;
 	f->tcp_flags = tcp_flags;
 	f->probability = uint32_t(probability * RAND_MAX);
-	src_filter.Insert(src, 128, f);
+	auto prev = static_cast<Filter*>(src_filter.Insert(src, 128, f));
+	delete prev;
 	}
 
 void PacketFilter::AddSrc(Val* src, uint32_t tcp_flags, double probability)
@@ -13,7 +27,8 @@ void PacketFilter::AddSrc(Val* src, uint32_t tcp_flags, double probability)
 	Filter* f = new Filter;
 	f->tcp_flags = tcp_flags;
 	f->probability = uint32_t(probability * RAND_MAX);
-	src_filter.Insert(src, f);
+	auto prev = static_cast<Filter*>(src_filter.Insert(src, f));
+	delete prev;
 	}
 
 void PacketFilter::AddDst(const IPAddr& dst, uint32_t tcp_flags, double probability)
@@ -21,7 +36,8 @@ void PacketFilter::AddDst(const IPAddr& dst, uint32_t tcp_flags, double probabil
 	Filter* f = new Filter;
 	f->tcp_flags = tcp_flags;
 	f->probability = uint32_t(probability * RAND_MAX);
-	dst_filter.Insert(dst, 128, f);
+	auto prev = static_cast<Filter*>(dst_filter.Insert(dst, 128, f));
+	delete prev;
 	}
 
 void PacketFilter::AddDst(Val* dst, uint32_t tcp_flags, double probability)
@@ -29,27 +45,36 @@ void PacketFilter::AddDst(Val* dst, uint32_t tcp_flags, double probability)
 	Filter* f = new Filter;
 	f->tcp_flags = tcp_flags;
 	f->probability = uint32_t(probability * RAND_MAX);
-	dst_filter.Insert(dst, f);
+	auto prev = static_cast<Filter*>(dst_filter.Insert(dst, f));
+	delete prev;
 	}
 
 bool PacketFilter::RemoveSrc(const IPAddr& src)
 	{
-	return src_filter.Remove(src, 128) != 0;
+	auto f = static_cast<Filter*>(src_filter.Remove(src, 128));
+	delete f;
+	return f != nullptr;
 	}
 
 bool PacketFilter::RemoveSrc(Val* src)
 	{
-	return src_filter.Remove(src) != NULL;
+	auto f = static_cast<Filter*>(src_filter.Remove(src));
+	delete f;
+	return f != nullptr;
 	}
 
 bool PacketFilter::RemoveDst(const IPAddr& dst)
 	{
-	return dst_filter.Remove(dst, 128) != NULL;
+	auto f = static_cast<Filter*>(dst_filter.Remove(dst, 128));
+	delete f;
+	return f != nullptr;
 	}
 
 bool PacketFilter::RemoveDst(Val* dst)
 	{
-	return dst_filter.Remove(dst) != NULL;
+	auto f = static_cast<Filter*>(dst_filter.Remove(dst));
+	delete f;
+	return f != nullptr;
 	}
 
 bool PacketFilter::Match(const IP_Hdr* ip, int len, int caplen)
diff --git a/src/PacketFilter.h b/src/PacketFilter.h
index 1b5111800f..384ce503c5 100644
--- a/src/PacketFilter.h
+++ b/src/PacketFilter.h
@@ -7,7 +7,7 @@
 
 class PacketFilter {
 public:
-	explicit PacketFilter(bool arg_default)	{ default_match = arg_default; }
+	explicit PacketFilter(bool arg_default);
 	~PacketFilter()	{}
 
 	// Drops all packets from a particular source (which may be given
@@ -34,6 +34,8 @@ private:
 		uint32_t probability;
 	};
 
+	static void DeleteFilter(void* data);
+
 	bool MatchFilter(const Filter& f, const IP_Hdr& ip, int len, int caplen);
 
 	bool default_match;
diff --git a/src/PrefixTable.h b/src/PrefixTable.h
index 35da3533ed..e22a89fff8 100644
--- a/src/PrefixTable.h
+++ b/src/PrefixTable.h
@@ -18,8 +18,8 @@ private:
 	};
 
 public:
-	PrefixTable()	{ tree = New_Patricia(128); }
-	~PrefixTable()	{ Destroy_Patricia(tree, 0); }
+	PrefixTable()	{ tree = New_Patricia(128); delete_function = nullptr; }
+	~PrefixTable()	{ Destroy_Patricia(tree, delete_function); }
 
 	// Addr in network byte order. If data is zero, acts like a set.
 	// Returns ptr to old data if already existing.
@@ -43,7 +43,10 @@ public:
 	void* Remove(const IPAddr& addr, int width);
 	void* Remove(const Val* value);
 
-	void Clear()	{ Clear_Patricia(tree, 0); }
+	void Clear()	{ Clear_Patricia(tree, delete_function); }
+
+	// Sets a function to call for each node when table is cleared/destroyed.
+	void SetDeleteFunction(data_fn_t del_fn)	{ delete_function = del_fn; }
 
 	iterator InitIterator();
 	void* GetNext(iterator* i);
@@ -53,4 +56,5 @@ private:
 	static IPPrefix PrefixToIPPrefix(prefix_t* p);
 
 	patricia_tree_t* tree;
+	data_fn_t delete_function;
 };
diff --git a/src/patricia.c b/src/patricia.c
index 1928d8ed0e..27fe5e004c 100644
--- a/src/patricia.c
+++ b/src/patricia.c
@@ -432,7 +432,7 @@ New_Patricia (int maxbits)
  */
 
 void
-Clear_Patricia (patricia_tree_t *patricia, void_fn_t func)
+Clear_Patricia (patricia_tree_t *patricia, data_fn_t func)
 {
     assert (patricia);
     if (patricia->head) {
@@ -476,7 +476,7 @@ Clear_Patricia (patricia_tree_t *patricia, void_fn_t func)
 
 
 void
-Destroy_Patricia (patricia_tree_t *patricia, void_fn_t func)
+Destroy_Patricia (patricia_tree_t *patricia, data_fn_t func)
 {
     Clear_Patricia (patricia, func);
     Delete (patricia);
@@ -489,7 +489,7 @@ Destroy_Patricia (patricia_tree_t *patricia, void_fn_t func)
  */
 
 void
-patricia_process (patricia_tree_t *patricia, void_fn_t func)
+patricia_process (patricia_tree_t *patricia, prefix_data_fn_t func)
 {
     patricia_node_t *node;
     assert (func);
diff --git a/src/patricia.h b/src/patricia.h
index 819230be1d..a32c5e3e81 100644
--- a/src/patricia.h
+++ b/src/patricia.h
@@ -51,8 +51,6 @@
 
 #include <sys/types.h>
 
-/* typedef unsigned int u_int; */
-typedef void (*void_fn_t)();
 /* { from defs.h */
 #define prefix_touchar(prefix) ((u_char *)&(prefix)->add.sin)
 #define MAXLINE 1024
@@ -84,6 +82,9 @@ typedef struct _prefix_t {
     } add;
 } prefix_t;
 
+typedef void (*data_fn_t)(void*);
+typedef void (*prefix_data_fn_t)(prefix_t*, void*);
+
 /* } */
 
 typedef struct _patricia_node_t {
@@ -110,9 +111,9 @@ patricia_node_t * patricia_search_best2 (patricia_tree_t *patricia, prefix_t *pr
 patricia_node_t *patricia_lookup (patricia_tree_t *patricia, prefix_t *prefix);
 void patricia_remove (patricia_tree_t *patricia, patricia_node_t *node);
 patricia_tree_t *New_Patricia (int maxbits);
-void Clear_Patricia (patricia_tree_t *patricia, void_fn_t func);
-void Destroy_Patricia (patricia_tree_t *patricia, void_fn_t func);
-void patricia_process (patricia_tree_t *patricia, void_fn_t func);
+void Clear_Patricia (patricia_tree_t *patricia, data_fn_t func);
+void Destroy_Patricia (patricia_tree_t *patricia, data_fn_t func);
+void patricia_process (patricia_tree_t *patricia, prefix_data_fn_t func);
 
 void Deref_Prefix (prefix_t * prefix);