diff --git a/TODO b/TODO
index 2b172a0..c88912f 100644
--- a/TODO
+++ b/TODO
@@ -6,7 +6,6 @@ Technlology Preview 2 :
 - Refactor medium traversal to unify clouds, atmosphere and god rays.
 - Fix potential holes in land rendering (OpenGL and software).
 - Fix sun size not being consistent between opengl and software
-- Fix CanvasPortion saves colliding on disk when running several instances
 
 Technology Preview 3 :
 - Alter aerial perspective using estimation of the amount of light left after cloud layers traversal.
diff --git a/src/render/software/CanvasPortion.cpp b/src/render/software/CanvasPortion.cpp
index 932424d..1af36cc 100644
--- a/src/render/software/CanvasPortion.cpp
+++ b/src/render/software/CanvasPortion.cpp
@@ -1,11 +1,14 @@
 #include "CanvasPortion.h"
 
 #include <cassert>
+#include <stdlib.h>
+#include <vector>
 
 #include "CanvasPixel.h"
 #include "CanvasPreview.h"
 #include "PackStream.h"
 #include "FileSystem.h"
+#include "System.h"
 
 #define CHECK_COORDINATES()                                                                                            \
     assert(x >= 0);                                                                                                    \
@@ -14,6 +17,15 @@
     assert(y < height);                                                                                                \
     assert(pixels != NULL)
 
+// Keep track of created files to erase them at program exit
+static std::vector<std::string> _files;
+static void clean_all_files() {
+    for (auto &filepath : _files) {
+        FileSystem::removeFile(filepath);
+    }
+}
+static int _atexit = std::atexit(clean_all_files);
+
 CanvasPortion::CanvasPortion(int index, CanvasPreview *preview) : index(index), preview(preview) {
     width = 1;
     height = 1;
@@ -73,7 +85,9 @@ void CanvasPortion::discardPixels(bool save) {
 
 void CanvasPortion::saveToDisk() {
     if (pixels) {
-        filepath = FileSystem::getTempFile("paysages_portion_" + std::to_string(index) + ".dat");
+        auto pid = System::getProcessId();
+        filepath =
+            FileSystem::getTempFile("paysages_portion_" + std::to_string(index) + "_" + std::to_string(pid) + ".dat");
         PackStream stream;
         stream.bindToFile(filepath, true);
         stream.write(&width);
@@ -83,6 +97,7 @@ void CanvasPortion::saveToDisk() {
                 pixels[y * width + x].getComposite().save(&stream);
             }
         }
+        _files.push_back(filepath);
     }
 }
 
diff --git a/src/system/FileSystem.cpp b/src/system/FileSystem.cpp
index 11d31ec..8d1d961 100644
--- a/src/system/FileSystem.cpp
+++ b/src/system/FileSystem.cpp
@@ -2,6 +2,7 @@
 
 #include <QDir>
 #include <QFileInfo>
+#include <cstdio>
 
 std::string FileSystem::getTempFile(const std::string &filename) {
     return QDir::temp().filePath(QString::fromStdString(filename)).toStdString();
@@ -10,3 +11,9 @@ std::string FileSystem::getTempFile(const std::string &filename) {
 bool FileSystem::isFile(const std::string &filepath) {
     return QFileInfo(QString::fromStdString(filepath)).exists();
 }
+
+bool FileSystem::removeFile(const std::string &filepath) {
+    if (FileSystem::isFile(filepath)) {
+        remove(filepath.c_str());
+    }
+}
diff --git a/src/system/FileSystem.h b/src/system/FileSystem.h
index 5e8963a..2acd06c 100644
--- a/src/system/FileSystem.h
+++ b/src/system/FileSystem.h
@@ -19,6 +19,11 @@ class SYSTEMSHARED_EXPORT FileSystem {
      * Returns true if the given path points to a file.
      */
     static bool isFile(const std::string &filepath);
+
+    /**
+     * Remove a file by its absolute path.
+     */
+    static bool removeFile(const std::string &filepath);
 };
 }
 }
diff --git a/src/system/PackStream.cpp b/src/system/PackStream.cpp
index 0e90ef4..1716866 100644
--- a/src/system/PackStream.cpp
+++ b/src/system/PackStream.cpp
@@ -133,6 +133,6 @@ void PackStream::skip(const double &value, int count) {
     stream->skipRawData(sizeof(value) * count);
 }
 
-void paysages::system::PackStream::skipBytes(int bytes) {
+void PackStream::skipBytes(int bytes) {
     stream->skipRawData(bytes);
 }
diff --git a/src/system/System.cpp b/src/system/System.cpp
index 3eb559e..7a79d7a 100644
--- a/src/system/System.cpp
+++ b/src/system/System.cpp
@@ -1,6 +1,7 @@
 #include "System.h"
 
 #include <QThread>
+#include <QCoreApplication>
 
 static int core_count = -1;
 
@@ -18,3 +19,7 @@ int System::getCoreCount() {
     }
     return core_count;
 }
+
+int System::getProcessId() {
+    return QCoreApplication::applicationPid();
+}
diff --git a/src/system/System.h b/src/system/System.h
index 9c5d4d6..4ea3ba9 100644
--- a/src/system/System.h
+++ b/src/system/System.h
@@ -11,7 +11,15 @@ namespace system {
  */
 class SYSTEMSHARED_EXPORT System {
   public:
+    /**
+     * Get the number of CPU cores available on current system.
+     */
     static int getCoreCount();
+
+    /**
+     * Get an identifying number for the current process.
+     */
+    static int getProcessId();
 };
 }
 }