diff --git a/poincare/include/poincare/zoom.h b/poincare/include/poincare/zoom.h
index 079f9a38e..132071d20 100644
--- a/poincare/include/poincare/zoom.h
+++ b/poincare/include/poincare/zoom.h
@@ -24,6 +24,7 @@ public:
   static void FullRange(ValueAtAbscissa evaluation, float tMin, float tMax, float tStep, float * fMin, float * fMax, Context * context, const void * auxiliary);
 
   static void CombineRanges(int length, const float * mins, const float * maxs, float * minRes, float * maxRes);
+  static void SanitizeRange(float * xMin, float * xMax, float * yMin, float * yMax, float normalRatio);
 
   /* If shrink is false, the range will be set to ratio by increasing the size
    * of the smallest axis. If it is true, the longest axis will be reduced.*/
diff --git a/poincare/src/zoom.cpp b/poincare/src/zoom.cpp
index d03cb5ff0..e18c0ebfb 100644
--- a/poincare/src/zoom.cpp
+++ b/poincare/src/zoom.cpp
@@ -237,6 +237,40 @@ void Zoom::CombineRanges(int length, const float * mins, const float * maxs, flo
   }
 }
 
+void Zoom::SanitizeRange(float * xMin, float * xMax, float * yMin, float * yMax, float normalRatio) {
+  /* Axes of the window can be :
+   *   - well-formed
+   *   - empty (min = max)
+   *   - ill-formed (min > max, or either bound is not finite)
+   *
+   * The general strategy to sanitize a window is as follow :
+   *   - for all ill-formed axes, set both bounds to 0
+   *   - if both axes are empty, set the X axis to default bounds
+   *   - if one axis is empty, normalize the window
+   *   - do nothing if both axes are well-formed. */
+
+  if (!std::isfinite(*xMin) || !std::isfinite(*xMax) || *xMax < *xMin) {
+    *xMin = 0;
+    *xMax = 0;
+  }
+  if (!std::isfinite(*yMin) || !std::isfinite(*yMax) || *yMax < *yMin) {
+    *yMin = 0;
+    *yMax = 0;
+  }
+
+  float xRange = *xMax - *xMin;
+  float yRange = *yMax - *yMin;
+  if (xRange < k_minimalRangeLength && yRange < k_minimalRangeLength) {
+    *xMax = *xMin + k_defaultHalfRange;
+    *xMin -= k_defaultHalfRange;
+    xRange = 2 * k_defaultHalfRange;
+  }
+
+  if (xRange < k_minimalRangeLength || yRange < k_minimalRangeLength) {
+    SetToRatio(normalRatio, xMin, xMax, yMin, yMax, false);
+  }
+}
+
 void Zoom::SetToRatio(float yxRatio, float * xMin, float * xMax, float * yMin, float * yMax, bool shrink) {
   float currentRatio = (*yMax - *yMin) / (*xMax - *xMin);