diff --git a/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp b/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp
index c4463f50fcc12a0bae7482ab2cdee03f7b8abf0f..b25ab59f2725437ccc1e7a25dacbfa10a6d52863 100644
--- a/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp
+++ b/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp
@@ -376,7 +376,7 @@ G1YoungGenSizer::G1YoungGenSizer() : _sizer_kind(SizerDefaults), _adaptive_size(
                              MAX2((uint) (MaxNewSize / HeapRegion::GrainBytes),
                                   1U);
       _sizer_kind = SizerMaxAndNewSize;
-      _adaptive_size = _min_desired_young_length == _max_desired_young_length;
+      _adaptive_size = _min_desired_young_length != _max_desired_young_length;
     } else {
       _sizer_kind = SizerNewSizeOnly;
     }
diff --git a/src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp b/src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp
index 96e4dc63dd27688e4b5477ee6538aab8f2294221..d15dee26c5d02cb2a4cd32099bdea3187ace9aae 100644
--- a/src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp
+++ b/src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp
@@ -133,7 +133,11 @@ private:
   SizerKind _sizer_kind;
   uint _min_desired_young_length;
   uint _max_desired_young_length;
+
+  // False when using a fixed young generation size due to command-line options,
+  // true otherwise.
   bool _adaptive_size;
+
   uint calculate_default_min_length(uint new_number_of_heap_regions);
   uint calculate_default_max_length(uint new_number_of_heap_regions);