From 2ec7484846875708078b45eb3ed32a814a6a7bbb Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@users.noreply.github.com>
Date: Thu, 3 Jan 2019 10:33:20 +1100
Subject: [PATCH] Removed log2

---
 src/_imaging.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/_imaging.c b/src/_imaging.c
index c209f4dc3..5ad3c154e 100644
--- a/src/_imaging.c
+++ b/src/_imaging.c
@@ -85,6 +85,9 @@
 
 #include "py3.h"
 
+#define _USE_MATH_DEFINES
+#include <math.h>
+
 /* Configuration stuff. Feel free to undef things you don't need. */
 #define WITH_IMAGECHOPS /* ImageChops support */
 #define WITH_IMAGEDRAW /* ImageDraw support */
@@ -1274,7 +1277,7 @@ _entropy(ImagingObject* self, PyObject* args)
     fentropy = 0.0;
     for (idx = 0; idx < length; idx++) {
         p = (double)h->histogram[idx] / fsum;
-        fentropy += p != 0.0 ? (p * log2(p)) : 0.0;
+        fentropy += p != 0.0 ? (p * log(p) * M_LOG2E) : 0.0;
     }
 
     /* Finally, allocate a PyObject* for return */