diff --git a/apps/probability/Makefile b/apps/probability/Makefile
index dd36d2129..2557b86c2 100644
--- a/apps/probability/Makefile
+++ b/apps/probability/Makefile
@@ -1,10 +1,9 @@
 app_objs += $(addprefix apps/probability/,\
   app.o\
-  calculation.o\
-  left_integral_calculation.o\
-  right_integral_calculation.o\
-  finite_integral_calculation.o\
-  calculation.o\
+  calculation/calculation.o\
+  calculation/left_integral_calculation.o\
+  calculation/right_integral_calculation.o\
+  calculation/finite_integral_calculation.o\
   calculation_controller.o\
   cell.o\
   image_table_view.o\
diff --git a/apps/probability/calculation.cpp b/apps/probability/calculation/calculation.cpp
similarity index 100%
rename from apps/probability/calculation.cpp
rename to apps/probability/calculation/calculation.cpp
diff --git a/apps/probability/calculation.h b/apps/probability/calculation/calculation.h
similarity index 96%
rename from apps/probability/calculation.h
rename to apps/probability/calculation/calculation.h
index e76ced3e3..58c4333c3 100644
--- a/apps/probability/calculation.h
+++ b/apps/probability/calculation/calculation.h
@@ -1,7 +1,7 @@
 #ifndef PROBABILITE_CALCULATION_H
 #define PROBABILITE_CALCULATION_H
 
-#include "law/law.h"
+#include "../law/law.h"
 
 namespace Probability {
 
diff --git a/apps/probability/finite_integral_calculation.cpp b/apps/probability/calculation/finite_integral_calculation.cpp
similarity index 100%
rename from apps/probability/finite_integral_calculation.cpp
rename to apps/probability/calculation/finite_integral_calculation.cpp
diff --git a/apps/probability/finite_integral_calculation.h b/apps/probability/calculation/finite_integral_calculation.h
similarity index 100%
rename from apps/probability/finite_integral_calculation.h
rename to apps/probability/calculation/finite_integral_calculation.h
diff --git a/apps/probability/left_integral_calculation.cpp b/apps/probability/calculation/left_integral_calculation.cpp
similarity index 100%
rename from apps/probability/left_integral_calculation.cpp
rename to apps/probability/calculation/left_integral_calculation.cpp
diff --git a/apps/probability/left_integral_calculation.h b/apps/probability/calculation/left_integral_calculation.h
similarity index 100%
rename from apps/probability/left_integral_calculation.h
rename to apps/probability/calculation/left_integral_calculation.h
diff --git a/apps/probability/right_integral_calculation.cpp b/apps/probability/calculation/right_integral_calculation.cpp
similarity index 100%
rename from apps/probability/right_integral_calculation.cpp
rename to apps/probability/calculation/right_integral_calculation.cpp
diff --git a/apps/probability/right_integral_calculation.h b/apps/probability/calculation/right_integral_calculation.h
similarity index 100%
rename from apps/probability/right_integral_calculation.h
rename to apps/probability/calculation/right_integral_calculation.h
diff --git a/apps/probability/calculation_controller.cpp b/apps/probability/calculation_controller.cpp
index 4f9a6cb9e..2a042a020 100644
--- a/apps/probability/calculation_controller.cpp
+++ b/apps/probability/calculation_controller.cpp
@@ -1,6 +1,9 @@
 #include "calculation_controller.h"
 #include "../constant.h"
 #include "../apps_container.h"
+#include "calculation/left_integral_calculation.h"
+#include "calculation/right_integral_calculation.h"
+#include "calculation/finite_integral_calculation.h"
 #include <assert.h>
 
 namespace Probability {
diff --git a/apps/probability/calculation_controller.h b/apps/probability/calculation_controller.h
index 9715c3a3e..bcf95f76a 100644
--- a/apps/probability/calculation_controller.h
+++ b/apps/probability/calculation_controller.h
@@ -5,6 +5,7 @@
 #include "law/law.h"
 #include "law_curve_view.h"
 #include "image_table_view.h"
+#include "calculation/calculation.h"
 
 namespace Probability {
 
diff --git a/apps/probability/image_table_view.h b/apps/probability/image_table_view.h
index f36fdc837..89fadfa93 100644
--- a/apps/probability/image_table_view.h
+++ b/apps/probability/image_table_view.h
@@ -2,9 +2,7 @@
 #define PROBABILITY_IMAGE_TABLE_VIEW_H
 
 #include <escher.h>
-#include "left_integral_calculation.h"
-#include "right_integral_calculation.h"
-#include "finite_integral_calculation.h"
+#include "calculation/calculation.h"
 
 namespace Probability {