diff --git a/DIRECTORY.md b/DIRECTORY.md
index 3f0a5dbb1..aad6c72aa 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -86,7 +86,7 @@
   * [Baconian Cipher](ciphers/baconian_cipher.py)
   * [Base16](ciphers/base16.py)
   * [Base32](ciphers/base32.py)
-  * [Base64](ciphers/base64.py)
+  * [Base64 Cipher](ciphers/base64_cipher.py)
   * [Base85](ciphers/base85.py)
   * [Beaufort Cipher](ciphers/beaufort_cipher.py)
   * [Bifid](ciphers/bifid.py)
@@ -1331,7 +1331,7 @@
   * [Title](strings/title.py)
   * [Top K Frequent Words](strings/top_k_frequent_words.py)
   * [Upper](strings/upper.py)
-  * [Wave](strings/wave.py)
+  * [Wave String](strings/wave_string.py)
   * [Wildcard Pattern Matching](strings/wildcard_pattern_matching.py)
   * [Word Occurrence](strings/word_occurrence.py)
   * [Word Patterns](strings/word_patterns.py)
diff --git a/ciphers/base64.py b/ciphers/base64_cipher.py
similarity index 100%
rename from ciphers/base64.py
rename to ciphers/base64_cipher.py
diff --git a/project_euler/problem_002/sol4.py b/project_euler/problem_002/sol4.py
index 3a2e4fce3..a13d34fd7 100644
--- a/project_euler/problem_002/sol4.py
+++ b/project_euler/problem_002/sol4.py
@@ -61,7 +61,7 @@ def solution(n: int = 4000000) -> int:
     if n <= 0:
         raise ValueError("Parameter n must be greater than or equal to one.")
     getcontext().prec = 100
-    phi = (Decimal(5) ** Decimal(0.5) + 1) / Decimal(2)
+    phi = (Decimal(5) ** Decimal("0.5") + 1) / Decimal(2)
 
     index = (math.floor(math.log(n * (phi + 2), phi) - 1) // 3) * 3 + 2
     num = Decimal(round(phi ** Decimal(index + 1))) / (phi + 2)
diff --git a/strings/wave.py b/strings/wave_string.py
similarity index 100%
rename from strings/wave.py
rename to strings/wave_string.py