diff --git a/imgui.h b/imgui.h
index a7e5fd7..1db78b4 100644
--- a/imgui.h
+++ b/imgui.h
@@ -1276,7 +1276,7 @@
     inline const T*     find(const T& v) const              { const T* data = Data;  const T* data_end = Data + Size; while (data < data_end) if (*data == v) break; else ++data; return data; }
     inline bool         find_erase(const T& v)              { const T* it = find(v); if (it < Data + Size) { erase(it); return true; } return false; }
     inline bool         find_erase_unsorted(const T& v)     { const T* it = find(v); if (it < Data + Size) { erase_unsorted(it); return true; } return false; }
-    inline int          index_from_ptr(const T* it) const   { IM_ASSERT(it >= Data && it <= Data+Size); const ptrdiff_t off = it - Data; return (int)off; }
+    inline int          index_from_ptr(const T* it) const   { IM_ASSERT(it >= Data && it < Data + Size); const ptrdiff_t off = it - Data; return (int)off; }
 };
 
 //-----------------------------------------------------------------------------