diff --git a/Spiral-Topography.md b/Spiral-Topography.md
index b89872f..eb0394d 100644
--- a/Spiral-Topography.md
+++ b/Spiral-Topography.md
@@ -52,7 +52,7 @@ uint16_t Map(uint16_t ring, uint16_t pixel) const {
   return index;
 }
 ```
-NOTE: The code above `(sizeof(Rings)/sizeof(Rings[0])` is a way of having the compiler calculate the count of elements in the Rings array without us hardcoding anything.  Often this is exposed as `_countof()` in many code based but it was not included in the Arduino headers for some reason.
+NOTE: The code above `(sizeof(Rings)/sizeof(Rings[0])` is a way of having the compiler calculate the count of elements in the Rings array without us hardcoding anything.  Often this is exposed as `_countof()` in many code bases but it was not included in the Arduino headers for some reason.
 
 ### Making the object usable for different collections of rings
 The above code hard codes the array of values.  We can make this a configuration argument to the constructor of our mapping class and thus reuse the code for different projects.