diff --git a/src/letsbuilda/imsosorrybutinparentheses.clj b/src/letsbuilda/imsosorrybutinparentheses.clj
index c8f3f93..e094462 100644
--- a/src/letsbuilda/imsosorrybutinparentheses.clj
+++ b/src/letsbuilda/imsosorrybutinparentheses.clj
@@ -1,6 +1,6 @@
 (ns letsbuilda.imsosorrybutinparentheses)
 
-(defn foo
-  "I don't do a whole lot."
-  [x]
-  (prn x "Hello, World!"))
+(def regex-word-replace (re-pattern "(?<!w)[lr](?!w)"))
+
+(defn char-replace [text]
+  (clojure.string/replace text regex-word-replace "w"))
diff --git a/test/letsbuilda/imsosorrybutinparentheses_test.clj b/test/letsbuilda/imsosorrybutinparentheses_test.clj
index 6416acf..db7129e 100644
--- a/test/letsbuilda/imsosorrybutinparentheses_test.clj
+++ b/test/letsbuilda/imsosorrybutinparentheses_test.clj
@@ -2,6 +2,13 @@
   (:require [clojure.test :refer :all]
             [letsbuilda.imsosorrybutinparentheses :refer :all]))
 
-(deftest a-test
-  (testing "FIXME, I fail."
-    (is (= 0 1))))
+(deftest char-replace-test
+  (testing "Replacing 'l' and 'r' with 'w' when not surrounded by 'w'"
+    (is (= "hewwo wowwd" (char-replace "hello world"))) ;; basic case
+    (is (= "woww" (char-replace "roll")))               ;; both 'r' and 'l' replaced
+    (is (= "wawe" (char-replace "rare")))               ;; 'r' in the middle replaced
+    (is (= "wlwlwl" (char-replace "wlwlwl")))           ;; no replacements where 'w' is involved
+    (is (= "w" (char-replace "l")))                     ;; single character replaced
+    (is (= "w" (char-replace "r")))                     ;; single character replaced
+    (is (= "" (char-replace "")))                       ;; edge case: empty string
+    ))