diff --git a/bin/phishing_catcher.py b/bin/phishing_catcher.py
index f497ddd..5da17d2 100644
--- a/bin/phishing_catcher.py
+++ b/bin/phishing_catcher.py
@@ -40,7 +40,7 @@
 app_home   = "{}/etc/apps/OSweep".format(os.environ['SPLUNK_HOME'])
 tp_modules = "{}/bin/_tp_modules".format(app_home)
 sys.path.insert(0, tp_modules)
-import entropy
+import math
 import pylev
 import tld
 import yaml
@@ -60,6 +60,12 @@ def get_modules():
         return
     return suspicious, confusables
 
+def entropy(string):
+    """Calculates the Shannon entropy of a string"""
+    prob = [ float(string.count(c)) / len(string) for c in dict.fromkeys(list(string)) ]
+    entropy = - sum([ p * math.log(p) / math.log(2.0) for p in prob ])
+    return entropy
+
 def request_module(session, filename):
     """Return a list of tags."""
     base_url = "https://raw.githubusercontent.com/x0rz/phishing_catcher/master{}"
@@ -125,7 +131,7 @@ def score_domain(provided_ioc):
     except Exception:
         domain = provided_ioc
 
-    score += int(round(entropy.shannon_entropy(domain)*50))
+    score += int(round(entropy(domain)*10))
     domain = confusables.unconfuse(domain)
     words_in_domain = re.split("\W+", domain)
 
diff --git a/bin/requirements.txt b/bin/requirements.txt
index c2b703a..689313f 100644
--- a/bin/requirements.txt
+++ b/bin/requirements.txt
@@ -1,5 +1,4 @@
 bs4
-entropy
 HTMLParser
 pylev
 PySocks