diff --git a/src/SFML/Window/Joystick.cpp b/src/SFML/Window/Joystick.cpp
index ca6818635..9989e3e8a 100644
--- a/src/SFML/Window/Joystick.cpp
+++ b/src/SFML/Window/Joystick.cpp
@@ -28,6 +28,8 @@
 #include <SFML/Window/Joystick.hpp>
 #include <SFML/Window/JoystickManager.hpp>
 
+#include <cassert>
+
 
 namespace sf
 {
@@ -55,6 +57,7 @@ bool Joystick::hasAxis(unsigned int joystick, Axis axis)
 ////////////////////////////////////////////////////////////
 bool Joystick::isButtonPressed(unsigned int joystick, unsigned int button)
 {
+    assert(button < Joystick::ButtonCount && "Button must be less than Joystick::ButtonCount");
     return priv::JoystickManager::getInstance().getState(joystick).buttons[button];
 }
 
diff --git a/src/SFML/Window/JoystickManager.cpp b/src/SFML/Window/JoystickManager.cpp
index 1719cd731..c6e5b3dab 100644
--- a/src/SFML/Window/JoystickManager.cpp
+++ b/src/SFML/Window/JoystickManager.cpp
@@ -27,6 +27,8 @@
 ////////////////////////////////////////////////////////////
 #include <SFML/Window/JoystickManager.hpp>
 
+#include <cassert>
+
 
 namespace sf::priv
 {
@@ -41,6 +43,7 @@ JoystickManager& JoystickManager::getInstance()
 ////////////////////////////////////////////////////////////
 const JoystickCaps& JoystickManager::getCapabilities(unsigned int joystick) const
 {
+    assert(joystick < Joystick::Count && "Joystick index must be less than Joystick::Count");
     return m_joysticks[joystick].capabilities;
 }
 
@@ -48,6 +51,7 @@ const JoystickCaps& JoystickManager::getCapabilities(unsigned int joystick) cons
 ////////////////////////////////////////////////////////////
 const JoystickState& JoystickManager::getState(unsigned int joystick) const
 {
+    assert(joystick < Joystick::Count && "Joystick index must be less than Joystick::Count");
     return m_joysticks[joystick].state;
 }
 
@@ -55,6 +59,7 @@ const JoystickState& JoystickManager::getState(unsigned int joystick) const
 ////////////////////////////////////////////////////////////
 const Joystick::Identification& JoystickManager::getIdentification(unsigned int joystick) const
 {
+    assert(joystick < Joystick::Count && "Joystick index must be less than Joystick::Count");
     return m_joysticks[joystick].identification;
 }