diff --git a/test/string-processing-test.fnl b/test/string-processing-test.fnl
index 7a49009..b4c6c84 100644
--- a/test/string-processing-test.fnl
+++ b/test/string-processing-test.fnl
@@ -12,6 +12,13 @@
   (fn range [start-line start-col end-line end-col]
     {:start (position start-line start-col) :end (position end-line   end-col)})
 
+  ;; "a" U+0061  is in  U+0000 to  U+007F, and therefore is 1 byte  in UTF-8, and 1 codepoint  in UTF-16
+  ;; "λ" U+03BB  is in  U+0080 to  U+07FF, and therefore is 2 bytes in UTF-8, and 1 codepoint  in UTF-16
+  ;; "ｾ" U+FF7E  is in  U+0800 to  U+FFFF, and therefore is 3 bytes in UTF-8, and 1 codepoint  in UTF-16
+  ;; "𐐀" U+10400 is in U+10000 to U+10FFFF,and therefore is 4 bytes in UTF-8, and 2 codepoints in UTF-16
+  ;; These symbols cover each of the four cases of byte/codepoint widths
+  ;; they should be sufficient for testing
+
   (it "converts position->byte properly"
     (is.equal 1 (utils.position->byte "a𐐀λ\nbλ𐐀" (position 0 0) :utf-8))
     (is.equal 2 (utils.position->byte "a𐐀λ\nbλ𐐀" (position 0 1) :utf-8))
@@ -28,7 +35,10 @@
     (is.equal 9 (utils.position->byte "a𐐀λ\nbλ𐐀" (position 1 0) :utf-16))
     (is.equal 10 (utils.position->byte "a𐐀λ\nbλ𐐀" (position 1 1) :utf-16))
     (is.equal 12 (utils.position->byte "a𐐀λ\nbλ𐐀" (position 1 2) :utf-16))
-    (is.equal 16 (utils.position->byte "a𐐀λ\nbλ𐐀" (position 1 4) :utf-16)))
+    (is.equal 16 (utils.position->byte "a𐐀λ\nbλ𐐀" (position 1 4) :utf-16))
+    (is.equal 19 (utils.position->byte "a𐐀ｾλ\nbλ𐐀" (position 1 4) :utf-16))
+    (is.equal 19 (utils.position->byte "a𐐀ｾλ\nbλ𐐀" (position 1 4) :utf-16))
+    (is.equal 7 (utils.position->byte "ｾｾ" (position 0 2) :utf-16)))
 
   (it "converts byte->position properly"
     (is.same (position 0 0) (utils.byte->position "a𐐀λ\nbλ𐐀" 1 :utf-8))
@@ -46,7 +56,10 @@
     (is.same (position 1 0) (utils.byte->position "a𐐀λ\nbλ𐐀" 9 :utf-16))
     (is.same (position 1 1) (utils.byte->position "a𐐀λ\nbλ𐐀" 10 :utf-16))
     (is.same (position 1 2) (utils.byte->position "a𐐀λ\nbλ𐐀" 12 :utf-16))
-    (is.same (position 1 4) (utils.byte->position "a𐐀λ\nbλ𐐀" 16 :utf-16)))
+    (is.same (position 1 4) (utils.byte->position "a𐐀λ\nbλ𐐀" 16 :utf-16))
+    (is.same (position 1 4) (utils.byte->position "a𐐀ｾλ\nbλ𐐀" 19 :utf-16))
+    (is.same (position 1 4) (utils.byte->position "a𐐀ｾλ\nbλ𐐀" 19 :utf-16))
+    (is.same (position 0 2) (utils.byte->position "ｾｾ" 7 :utf-16)))
 
   (describe "apply-changes"