diff --git a/apps/shared/interval_parameter_controller.cpp b/apps/shared/interval_parameter_controller.cpp
index b1e3f1068..2876597a3 100644
--- a/apps/shared/interval_parameter_controller.cpp
+++ b/apps/shared/interval_parameter_controller.cpp
@@ -1,5 +1,4 @@
 #include "interval_parameter_controller.h"
-#include <assert.h>
 
 namespace Shared {
 
@@ -33,10 +32,6 @@ void IntervalParameterController::willDisplayCellForIndex(HighlightCell * cell,
   FloatParameterController::willDisplayCellForIndex(cell, index);
 }
 
-Interval * IntervalParameterController::interval() {
-  return m_interval;
-}
-
 double IntervalParameterController::parameterAtIndex(int index) {
   GetterPointer getters[k_totalNumberOfCell] = {&Interval::start, &Interval::end, &Interval::step};
   return (m_interval->*getters[index])();
diff --git a/apps/shared/interval_parameter_controller.h b/apps/shared/interval_parameter_controller.h
index fbcc97cdc..b7e9b7d4a 100644
--- a/apps/shared/interval_parameter_controller.h
+++ b/apps/shared/interval_parameter_controller.h
@@ -4,13 +4,14 @@
 #include <escher.h>
 #include "interval.h"
 #include "float_parameter_controller.h"
+#include <assert.h>
 
 namespace Shared {
 
 class IntervalParameterController : public Shared::FloatParameterController<double> {
 public:
   IntervalParameterController(Responder * parentResponder, InputEventHandlerDelegate * inputEventHandlerDelegate, Interval * interval);
-  Interval * interval();
+  Interval * interval() { assert(m_interval); return m_interval; }
   const char * title() override;
   void setTitle(I18n::Message title) { m_title = title; }
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;