diff --git a/lib/build.mk b/lib/build.mk
index 6c93d99c..3baf2ec0 100644
--- a/lib/build.mk
+++ b/lib/build.mk
@@ -8,6 +8,7 @@ LIBFLUXENGINE_SRCS = \
 	lib/decoders/fluxmapreader.cc \
 	lib/decoders/fmmfm.cc \
 	lib/encoders/encoders.cc \
+	lib/environment.cc \
 	lib/flags.cc \
 	lib/fluxmap.cc \
 	lib/fluxsink/a2rfluxsink.cc \
diff --git a/lib/environment.cc b/lib/environment.cc
new file mode 100644
index 00000000..feda7fd5
--- /dev/null
+++ b/lib/environment.cc
@@ -0,0 +1,17 @@
+#include "lib/globals.h"
+#include "lib/environment.h"
+
+static std::unique_ptr<std::set<LocalBase*>> variables;
+
+void Environment::reset()
+{
+    for (LocalBase* var : *variables)
+        var->reset();
+}
+
+void Environment::addVariable(LocalBase* local)
+{
+	if (!variables)
+		variables = std::make_unique<std::set<LocalBase*>>();
+    variables->insert(local);
+}
diff --git a/lib/environment.h b/lib/environment.h
new file mode 100644
index 00000000..1295b4d0
--- /dev/null
+++ b/lib/environment.h
@@ -0,0 +1,44 @@
+#ifndef ENVIRONMENT_H
+#define ENVIRONMENT_H
+
+class LocalBase;
+
+class Environment
+{
+public:
+    static void reset();
+    static void addVariable(LocalBase* local);
+};
+
+class LocalBase
+{
+public:
+    virtual void reset() = 0;
+};
+
+template <class T>
+class Local : LocalBase
+{
+public:
+    Local()
+    {
+        Environment::addVariable(this);
+    }
+    void reset() override
+    {
+        _value.clear();
+    }
+    T& operator*()
+    {
+        return _value;
+    }
+    T& operator->()
+    {
+        return _value;
+    }
+
+private:
+    T _value;
+};
+
+#endif
diff --git a/lib/layout.cc b/lib/layout.cc
index 8b3e51f6..2bbf8717 100644
--- a/lib/layout.cc
+++ b/lib/layout.cc
@@ -1,9 +1,11 @@
 #include "lib/globals.h"
 #include "lib/layout.h"
 #include "lib/proto.h"
+#include "lib/environment.h"
 #include <fmt/format.h>
 
-static std::map<std::pair<int, int>, std::unique_ptr<Layout>> layoutCache;
+static Local<std::map<std::pair<int, int>, std::unique_ptr<Layout>>>
+    layoutCache;
 
 std::vector<std::pair<int, int>> Layout::getTrackOrdering(
     unsigned guessedTracks, unsigned guessedSides)
@@ -66,7 +68,7 @@ static void expandSectors(const LayoutProto::SectorsProto& sectorsProto,
 
 const Layout& Layout::getLayoutOfTrack(unsigned track, unsigned side)
 {
-    auto& layout = layoutCache[std::make_pair(track, side)];
+    auto& layout = (*layoutCache)[std::make_pair(track, side)];
     if (!layout)
     {
         layout.reset(new Layout());
diff --git a/lib/readerwriter.cc b/lib/readerwriter.cc
index 8811af9b..42a8e96b 100644
--- a/lib/readerwriter.cc
+++ b/lib/readerwriter.cc
@@ -18,6 +18,7 @@
 #include "utils.h"
 #include "lib/config.pb.h"
 #include "proto.h"
+#include "environment.h"
 #include <optional>
 
 enum ReadResult
@@ -228,6 +229,7 @@ void writeTracks(FluxSink& fluxSink,
     std::function<bool(const Location& location)> verifier,
     const std::set<Location>& locations)
 {
+    Environment::reset();
     Logger() << BeginOperationLogMessage{"Encoding and writing to disk"};
 
     int index = 0;
@@ -416,6 +418,7 @@ void writeRawDiskCommand(FluxSource& fluxSource, FluxSink& fluxSink)
 std::shared_ptr<TrackFlux> readAndDecodeTrack(
     FluxSource& fluxSource, AbstractDecoder& decoder, const Location& location)
 {
+    Environment::reset();
     auto trackFlux = std::make_shared<TrackFlux>();
     trackFlux->location = location;
 
@@ -450,6 +453,7 @@ std::shared_ptr<TrackFlux> readAndDecodeTrack(
 std::shared_ptr<const DiskFlux> readDiskCommand(
     FluxSource& fluxSource, AbstractDecoder& decoder)
 {
+    Environment::reset();
     std::unique_ptr<FluxSink> outputFluxSink;
     if (config.decoder().has_copy_flux_to())
         outputFluxSink = FluxSink::create(config.decoder().copy_flux_to());
@@ -565,6 +569,7 @@ void rawReadDiskCommand(FluxSource& fluxsource, FluxSink& fluxsink)
 {
     Logger() << BeginOperationLogMessage{"Performing raw read of disk"};
 
+    Environment::reset();
     auto tracks = iterate(config.tracks());
     auto heads = iterate(config.heads());
     unsigned locations = tracks.size() * heads.size();