diff --git a/src/cpucounters.cpp b/src/cpucounters.cpp
index 470f9916..c8d7e034 100644
--- a/src/cpucounters.cpp
+++ b/src/cpucounters.cpp
@@ -3062,6 +3062,7 @@ PCM::PCM() :
 #ifdef PCM_USE_PERF
     canUsePerf = true;
     perfEventHandle.resize(num_cores, std::vector<int>(PERF_MAX_COUNTERS, -1));
+    std::fill(perfTopDownPos.begin(), perfTopDownPos.end(), 0);
 #endif
 
     for (int32 i = 0; i < num_cores; ++i)
diff --git a/src/pcm-accel-common.cpp b/src/pcm-accel-common.cpp
index c702e93c..dfd3f4ab 100644
--- a/src/pcm-accel-common.cpp
+++ b/src/pcm-accel-common.cpp
@@ -351,13 +351,16 @@ void readAccelCounters(SystemCounterState& sycs_)
 }
 
 AcceleratorCounterState* AcceleratorCounterState::instance = NULL;
+
+std::mutex instanceCreationMutexForAcceleratorCounterState{};
+
 AcceleratorCounterState * AcceleratorCounterState::getInstance()
  {
     // lock-free read
     // cppcheck-suppress identicalConditionAfterEarlyExit
     if (instance) return instance;
 
-    std::unique_lock<std::mutex> instanceCreationMutex;
+    std::unique_lock<std::mutex> _(instanceCreationMutexForAcceleratorCounterState);
     // cppcheck-suppress identicalConditionAfterEarlyExit
     if (instance) return instance;