diff --git a/general.hpp b/general.hpp
index b0bf033..1581f8e 100644
--- a/general.hpp
+++ b/general.hpp
@@ -303,6 +303,10 @@ class Player
 public:
   RCL_Camera mCamera;
   RCL_Unit mVericalSpeed;
+  RCL_Unit mVericalSpeedPrev; /* In order to detect whether player is standing
+                                 on ground (for jumping) we need the derivative
+                                 of vertical speed (not just the vertical
+                                 speed) => we need two values. */
   bool mRunning;
   RCL_Unit mHeadBob;
   bool mHeadBobUp;
@@ -319,6 +323,7 @@ public:
     mCamera.resolution.y = SCREEN_HEIGHT;
     mCamera.shear = 0;
     mVericalSpeed = 0;
+    mVericalSpeedPrev = 0;
     mRunning = false;
     mHeadBob = 0;
     mHeadBobUp = true;
@@ -390,15 +395,8 @@ public:
     if (heightDiff == 0)
       mVericalSpeed = 0; // hit floor/ceiling
 
-    if (jump && mVericalSpeed == 0)
-    {
-      int16_t camX = RCL_divRoundDown(mCamera.position.x,RCL_UNITS_PER_SQUARE);
-      int16_t camY = RCL_divRoundDown(mCamera.position.y,RCL_UNITS_PER_SQUARE);
-
-      if (mCamera.height - RCL_CAMERA_COLL_HEIGHT_BELOW -
-        floorHeightFunction(camX,camY) < 2)
-        mVericalSpeed = PLAYER_JUMP_SPEED; // jump
-    }     
+    if (jump && mVericalSpeed == 0 && mVericalSpeedPrev == 0)
+      mVericalSpeed = PLAYER_JUMP_SPEED; // jump
 
     if (shearDirection != 0)
       mCamera.shear = RCL_clamp(mCamera.shear + shearDirection * 10,
@@ -406,6 +404,8 @@ public:
     else
       mCamera.shear /= 2;
 
+    mVericalSpeedPrev = mVericalSpeed;
+
     if (computeHeight)
       mVericalSpeed -= (dt * GRAVITY_ACCELERATION) / 1000; // gravity
   }