diff --git a/scripts/base/frameworks/sumstats/plugins/topk.bro b/scripts/base/frameworks/sumstats/plugins/topk.bro
index 58f8168f5b..cb90af962e 100644
--- a/scripts/base/frameworks/sumstats/plugins/topk.bro
+++ b/scripts/base/frameworks/sumstats/plugins/topk.bro
@@ -18,18 +18,20 @@ export {
 
 }
 
+hook register_observe_plugins()
+	{
+	register_observe_plugin(TOPK, function(r: Reducer, val: double, obs: Observation, rv: ResultVal)
+		{
+		topk_add(rv$topk, obs);
+		});
+	}
+
 hook init_resultval_hook(r: Reducer, rv: ResultVal)
 	{
 	if ( TOPK in r$apply && ! rv?$topk )
 		rv$topk = topk_init(r$topk_size);
 	}
 
-hook observe_hook(r: Reducer, val: double, obs: Observation, rv: ResultVal)
-	{
-	if ( TOPK in r$apply )
-		topk_add(rv$topk, obs);
-	}
-
 hook compose_resultvals_hook(result: ResultVal, rv1: ResultVal, rv2: ResultVal)
 	{
 	if ( rv1?$topk )
diff --git a/testing/btest/scripts/base/frameworks/sumstats/topk-cluster.bro b/testing/btest/scripts/base/frameworks/sumstats/topk-cluster.bro
index 0ade38e86c..d26cee4244 100644
--- a/testing/btest/scripts/base/frameworks/sumstats/topk-cluster.bro
+++ b/testing/btest/scripts/base/frameworks/sumstats/topk-cluster.bro
@@ -23,27 +23,24 @@ event bro_init() &priority=5
 	{
 	local r1: SumStats::Reducer = [$stream="test.metric", 
 	                               $apply=set(SumStats::TOPK)];
-	SumStats::create([$epoch=5secs,
-	                     $reducers=set(r1),
-	                     $epoch_finished(data: SumStats::ResultTable) = 
-	                     	{
-	                     	for ( key in data )
-	                     		{
-	                     		local r = data[key]["test.metric"];
-					
-					local s: vector of SumStats::Observation;
-					s = topk_get_top(r$topk, 5);
-				
-					print fmt("Top entries for key %s", key$str);
-					for ( element in s ) 
-						{
-						print fmt("Num: %d, count: %d, epsilon: %d", s[element]$num, topk_count(r$topk, s[element]), topk_epsilon(r$topk, s[element]));
-						}
-
-					terminate();
-	                     		}
-	                     	}
-		 ]);
+	SumStats::create([$name="topk-test", 
+	                  $epoch=5secs,
+	                  $reducers=set(r1),
+	                  $epoch_result(ts: time, key: SumStats::Key, result: SumStats::Result) =
+	                  	{
+	                  	local r = result["test.metric"];
+	                  	local s: vector of SumStats::Observation;
+	                  	s = topk_get_top(r$topk, 5);
+	                  	print fmt("Top entries for key %s", key$str);
+	                  	for ( element in s ) 
+	                  		{
+	                  		print fmt("Num: %d, count: %d, epsilon: %d", s[element]$num, topk_count(r$topk, s[element]), topk_epsilon(r$topk, s[element]));
+	                  		}
+	                  	},
+	                  $epoch_finished(ts: time) = 
+	                  	{
+	                  	terminate();
+	                  	}]);
 
 
 	}
diff --git a/testing/btest/scripts/base/frameworks/sumstats/topk.bro b/testing/btest/scripts/base/frameworks/sumstats/topk.bro
index 22a5af1bc7..99c301c669 100644
--- a/testing/btest/scripts/base/frameworks/sumstats/topk.bro
+++ b/testing/btest/scripts/base/frameworks/sumstats/topk.bro
@@ -5,26 +5,21 @@ event bro_init() &priority=5
 	{
 	local r1: SumStats::Reducer = [$stream="test.metric", 
 	                               $apply=set(SumStats::TOPK)];
-	SumStats::create([$epoch=3secs,
-	                     $reducers=set(r1),
-	                     $epoch_finished(data: SumStats::ResultTable) = 
-	                     	{
-	                     	for ( key in data )
-	                     		{
-	                     		local r = data[key]["test.metric"];
-					
-					local s: vector of SumStats::Observation;
-					s = topk_get_top(r$topk, 5);
-				
-					print fmt("Top entries for key %s", key$str);
-					for ( element in s ) 
-						{
-						print fmt("Num: %d, count: %d, epsilon: %d", s[element]$num, topk_count(r$topk, s[element]), topk_epsilon(r$topk, s[element]));
-						}
-
-	                     		}
-	                     	}
-		 ]);
+	SumStats::create([$name="topk-test",
+	                  $epoch=3secs,
+	                  $reducers=set(r1),
+	                  $epoch_result(ts: time, key: SumStats::Key, result: SumStats::Result) =
+	                  	{
+	                  	local r = result["test.metric"];
+	                  	local s: vector of SumStats::Observation;
+	                  	s = topk_get_top(r$topk, 5);
+	                  	
+	                  	print fmt("Top entries for key %s", key$str);
+	                  	for ( element in s ) 
+	                  		{
+	                  		print fmt("Num: %d, count: %d, epsilon: %d", s[element]$num, topk_count(r$topk, s[element]), topk_epsilon(r$topk, s[element]));
+	                  		}
+	                  	}]);
 
 
 	const loop_v: vector of count = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100};