diff --git a/src/hotspot/share/gc/g1/g1SurvRateGroup.cpp b/src/hotspot/share/gc/g1/g1SurvRateGroup.cpp
index 15fc42d80fd..52e4033fd43 100644
--- a/src/hotspot/share/gc/g1/g1SurvRateGroup.cpp
+++ b/src/hotspot/share/gc/g1/g1SurvRateGroup.cpp
@@ -23,7 +23,6 @@
  */
 
 #include "precompiled.hpp"
-#include "gc/g1/g1CollectedHeap.inline.hpp"
 #include "gc/g1/g1HeapRegion.hpp"
 #include "gc/g1/g1Predictions.hpp"
 #include "gc/g1/g1SurvRateGroup.hpp"
@@ -57,10 +56,6 @@ void G1SurvRateGroup::reset() {
 
   // Seed initial _surv_rate_pred and _accum_surv_rate_pred values
   guarantee(_stats_arrays_length == 1, "invariant" );
-  guarantee(_surv_rate_predictors[0] != nullptr, "invariant" );
-  const double initial_surv_rate = 0.4;
-  _surv_rate_predictors[0]->add(initial_surv_rate);
-  _last_pred = _accum_surv_rate_pred[0] = initial_surv_rate;
 
   _num_added_regions = 0;
 }
@@ -75,8 +70,12 @@ void G1SurvRateGroup::stop_adding_regions() {
     _surv_rate_predictors = REALLOC_C_HEAP_ARRAY(TruncatedSeq*, _surv_rate_predictors, _num_added_regions, mtGC);
 
     for (size_t i = _stats_arrays_length; i < _num_added_regions; ++i) {
+      // Initialize predictors and accumulated survivor rate predictions.
       _surv_rate_predictors[i] = new TruncatedSeq(10);
+      _surv_rate_predictors[i]->add(InitialSurvivorRate);
+      _accum_surv_rate_pred[i] = ((i == 0) ? 0.0 : _accum_surv_rate_pred[i-1]) + InitialSurvivorRate;
     }
+    _last_pred = InitialSurvivorRate;
 
     _stats_arrays_length = _num_added_regions;
   }
@@ -96,6 +95,19 @@ void G1SurvRateGroup::all_surviving_words_recorded(const G1Predictions& predicto
   finalize_predictions(predictor);
 }
 
+double G1SurvRateGroup::accum_surv_rate_pred(uint age) const {
+  assert(_stats_arrays_length > 0, "invariant" );
+  double result;
+  if (age < _stats_arrays_length) {
+    result = _accum_surv_rate_pred[age];
+  } else {
+    double diff = (double)(age - _stats_arrays_length + 1);
+    result = _accum_surv_rate_pred[_stats_arrays_length - 1] + diff * _last_pred;
+  }
+  assert(result <= (age + 1.0), "Accumulated survivor rate %.2f must be smaller than age+1 %u", result, age + 1);
+  return result;
+}
+
 void G1SurvRateGroup::fill_in_last_surv_rates() {
   if (_num_added_regions > 0) { // conservative
     double surv_rate = _surv_rate_predictors[_num_added_regions-1]->last();
diff --git a/src/hotspot/share/gc/g1/g1SurvRateGroup.hpp b/src/hotspot/share/gc/g1/g1SurvRateGroup.hpp
index 1e1cc049caf..5522555f24a 100644
--- a/src/hotspot/share/gc/g1/g1SurvRateGroup.hpp
+++ b/src/hotspot/share/gc/g1/g1SurvRateGroup.hpp
@@ -52,6 +52,9 @@ class G1SurvRateGroup : public CHeapObj<mtGC> {
   uint _stats_arrays_length;
   uint _num_added_regions;   // The number of regions in this survivor rate group.
 
+  // The initial survivor rate for predictors. Somewhat random value.
+  const double InitialSurvivorRate = 0.4;
+
   double* _accum_surv_rate_pred;
   double  _last_pred;
   TruncatedSeq** _surv_rate_predictors;
@@ -73,15 +76,7 @@ public:
   void record_surviving_words(uint age, size_t surv_words);
   void all_surviving_words_recorded(const G1Predictions& predictor, bool update_predictors);
 
-  double accum_surv_rate_pred(uint age) const {
-    assert(_stats_arrays_length > 0, "invariant" );
-    if (age < _stats_arrays_length)
-      return _accum_surv_rate_pred[age];
-    else {
-      double diff = (double)(age - _stats_arrays_length + 1);
-      return _accum_surv_rate_pred[_stats_arrays_length - 1] + diff * _last_pred;
-    }
-  }
+  double accum_surv_rate_pred(uint age) const;
 
   double surv_rate_pred(G1Predictions const& predictor, uint age) const {
     assert(is_valid_age(age), "must be");