diff --git a/src/widget.cpp b/src/widget.cpp
index 377ef06677..9a9c3094aa 100644
--- a/src/widget.cpp
+++ b/src/widget.cpp
@@ -941,22 +941,6 @@ void NWidgetContainer::FillNestedArray(NWidgetBase **array, uint length)
 	}
 }
 
-/**
- * Return the biggest possible size of a nested widget.
- * @param base      Base size of the widget.
- * @param max_space Available space for the widget.
- * @param step      Stepsize of the widget.
- * @return Biggest possible size of the widget, assuming that \a base may only be incremented by \a step size steps.
- */
-static inline uint ComputeMaxSize(uint base, uint max_space, uint step)
-{
-	if (base >= max_space || step == 0) return base;
-	if (step == 1) return max_space;
-	int increment = max_space - base;
-	increment -= increment % step;
-	return base + increment;
-}
-
 /**
  * Widgets stacked on top of each other.
  */
diff --git a/src/widget_type.h b/src/widget_type.h
index fca5f3c560..29cb13acd9 100644
--- a/src/widget_type.h
+++ b/src/widget_type.h
@@ -485,6 +485,22 @@ private:
 	static Dimension closebox_dimension;  ///< Cached size of a closebox widget.
 };
 
+/**
+ * Return the biggest possible size of a nested widget.
+ * @param base      Base size of the widget.
+ * @param max_space Available space for the widget.
+ * @param step      Stepsize of the widget.
+ * @return Biggest possible size of the widget, assuming that \a base may only be incremented by \a step size steps.
+ */
+static FORCEINLINE uint ComputeMaxSize(uint base, uint max_space, uint step)
+{
+	if (base >= max_space || step == 0) return base;
+	if (step == 1) return max_space;
+	uint increment = max_space - base;
+	increment -= increment % step;
+	return base + increment;
+}
+
 /**
  * @defgroup NestedWidgetParts Hierarchical widget parts
  * To make nested widgets easier to enter, nested widget parts have been created. They allow the tree to be defined in a flat array of parts.