diff --git a/CHANGELOG.md b/CHANGELOG.md
index 80fb4a34..115ad654 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,14 @@
 Release notes
 =============
 
+Version 0.8.80
+--------------
+
+BUG FIX
+
+* Fix #357 group-aggreagate query in backward direction returns
+  invalid first/last values
+
 Version 0.8.79
 --------------
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 27b2b9a9..2b71aeb7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,7 +3,7 @@ cmake_minimum_required(VERSION 2.8)
 
 set(APP_VERSION_MAJOR "0")
 set(APP_VERSION_MINOR "8")
-set(APP_VERSION_PATCH "79")
+set(APP_VERSION_PATCH "80")
 string(TIMESTAMP APP_COMPILATION_TIME "%Y%m%d")
 
 set(APP_VERSION "${APP_VERSION_MAJOR}.${APP_VERSION_MINOR}.${APP_VERSION_PATCH}")
diff --git a/libakumuli/storage_engine/operators/operator.cpp b/libakumuli/storage_engine/operators/operator.cpp
index f5d8541f..67b46628 100644
--- a/libakumuli/storage_engine/operators/operator.cpp
+++ b/libakumuli/storage_engine/operators/operator.cpp
@@ -56,17 +56,19 @@ void AggregationResult::add(aku_Timestamp ts, double xs, bool forward) {
         maxts = ts;
     }
     if (cnt == 0) {
-        first = xs;
         if (forward) {
+            first = xs;
             _begin = ts;
         } else {
+            last = xs;
             _end = ts;
         }
     }
-    last = xs;
     if (forward) {
+        last = xs;
         _end = ts;
     } else {
+        first = xs;
         _begin = ts;
     }
     cnt += 1;
@@ -83,8 +85,6 @@ void AggregationResult::combine(const AggregationResult& other) {
         max = other.max;
         maxts = other.maxts;
     }
-    min = std::min(min, other.min);
-    max = std::max(max, other.max);
     if (_begin > other._begin) {
         first = other.first;
         _begin = other._begin;