diff --git a/apps/main.cpp b/apps/main.cpp
index 51a95e2b9ab..0ea75e8885e 100644
--- a/apps/main.cpp
+++ b/apps/main.cpp
@@ -2,19 +2,6 @@
 #include "global_preferences.h"
 #include <poincare/init.h>
 
-#if PLATFORM_DEVICE
-// On device, stack start address is always known. TODO : Factorize address
-static void * s_stackStart = reinterpret_cast<void *>(0x20000000 + 256*1024);
-#else
-// Stack start will be defined in ion_main.
-static void * s_stackStart = nullptr;
-#endif
-
-void * Ion::stackStart() {
-  assert(s_stackStart != nullptr);
-  return s_stackStart;
-}
-
 #define DUMMY_MAIN 0
 #if DUMMY_MAIN
 
@@ -80,7 +67,7 @@ void ion_main(int argc, const char * const argv[]) {
    * example, stack pointer could go backward after initialization and allocated
    * memory pointers could be overlooked during mark procedure. */
   volatile int stackTop;
-  s_stackStart = (void *)(&stackTop);
+  Ion::setStackStart((void *)(&stackTop));
 #endif
 
   AppsContainer::sharedAppsContainer()->run();
diff --git a/ion/Makefile b/ion/Makefile
index 1c325ebc654..6efea82b872 100644
--- a/ion/Makefile
+++ b/ion/Makefile
@@ -31,6 +31,7 @@ ion_src += $(addprefix ion/src/shared/, \
   events_keyboard.cpp \
   events_modifier.cpp \
   platform_info.cpp \
+  stack_position.cpp \
   storage.cpp \
   unicode/utf8_decoder.cpp\
   unicode/utf8_helper.cpp\
diff --git a/ion/include/ion.h b/ion/include/ion.h
index 47c01061449..e01bc03c1fb 100644
--- a/ion/include/ion.h
+++ b/ion/include/ion.h
@@ -46,8 +46,9 @@ uint32_t random();
 // Decompress data
 void decompress(const uint8_t * src, uint8_t * dst, int srcSize, int dstSize);
 
-// Returns address to the first object that can be allocated on stack
+// Sets and returns address to the first object that can be allocated on stack
 void * stackStart();
+void setStackStart(void *);
 // Tells whether the stack pointer is within acceptable bounds
 bool stackSafe();
 
diff --git a/ion/src/shared/stack_position.cpp b/ion/src/shared/stack_position.cpp
new file mode 100644
index 00000000000..9cb17b2ee76
--- /dev/null
+++ b/ion/src/shared/stack_position.cpp
@@ -0,0 +1,22 @@
+#include <ion.h>
+
+namespace Ion {
+
+#if PLATFORM_DEVICE
+// On device, stack start address is always known. TODO : Factorize address
+static void * s_stackStart = reinterpret_cast<void *>(0x20000000 + 256*1024);
+#else
+// Stack start will be defined in ion_main.
+static void * s_stackStart = nullptr;
+#endif
+
+void * stackStart() {
+  assert(s_stackStart != nullptr);
+  return s_stackStart;
+}
+
+void setStackStart(void * pointer) {
+  assert(pointer != nullptr);
+  s_stackStart = pointer;
+}
+}
\ No newline at end of file
diff --git a/quiz/src/runner.cpp b/quiz/src/runner.cpp
index ef4b883c3d9..996a7ec9673 100644
--- a/quiz/src/runner.cpp
+++ b/quiz/src/runner.cpp
@@ -31,10 +31,16 @@ static inline void ion_main_inner() {
 
 
 void ion_main(int argc, const char * const argv[]) {
-  // Initialize the backlight
   Ion::Backlight::init();
-  // Initialize Poincare::TreePool::sharedPool
-  Poincare::Init();
+  Poincare::Init(); // Initialize Poincare::TreePool::sharedPool
+#if !PLATFORM_DEVICE
+  /* s_stackStart must be defined as early as possible to ensure that there
+   * cannot be allocated memory pointers before. Otherwise, with MicroPython for
+   * example, stack pointer could go backward after initialization and allocated
+   * memory pointers could be overlooked during mark procedure. */
+  volatile int stackTop;
+  Ion::setStackStart((void *)(&stackTop));
+#endif
 
   Poincare::ExceptionCheckpoint ecp;
   if (ExceptionRun(ecp)) {