diff --git a/email2pdf b/email2pdf
index 5493b82..320afa2 100755
--- a/email2pdf
+++ b/email2pdf
@@ -255,14 +255,15 @@ def remove_invalid_urls(payload):
 
     for img in soup.find_all('img'):
         if img.has_attr('src'):
-            src = img['src'].lower()
-            if src == 'broken':
+            src = img['src']
+            lowerSrc = src.lower()
+            if lowerSrc == 'broken':
                 del img['src']
-            elif not (src.startswith('data')):
+            elif not (lowerSrc.startswith('data')):
                 foundBlacklist = False
 
                 for IMAGE_LOAD_BLACKLIST_ITEM in IMAGE_LOAD_BLACKLIST:
-                    if IMAGE_LOAD_BLACKLIST_ITEM in src:
+                    if IMAGE_LOAD_BLACKLIST_ITEM in lowerSrc:
                         foundBlacklist = True
 
                 if not foundBlacklist:
diff --git a/tests/BaseTestClasses.py b/tests/BaseTestClasses.py
index 435e35e..acce041 100644
--- a/tests/BaseTestClasses.py
+++ b/tests/BaseTestClasses.py
@@ -33,6 +33,7 @@ class Email2PDFTestCase(unittest.TestCase):
     NONEXIST_IMG = 'http://www.andrewferrier.com/nonexist.jpg'
     NONEXIST_IMG_BLACKLIST = 'http://www.emltrk.com/nonexist.jpg'
     EXIST_IMG = 'https://raw.githubusercontent.com/andrewferrier/email2pdf/master/tests/basi2c16.png'
+    EXIST_IMG_UPPERCASE = 'https://raw.githubusercontent.com/andrewferrier/email2pdf/master/tests/UPPERCASE.png'
     COMMAND = os.path.normpath(os.path.join(os.getcwd(), 'email2pdf'))
 
     DEFAULT_FROM = "from@example.org"
diff --git a/tests/Subprocess/test_Subprocess_MIME.py b/tests/Subprocess/test_Subprocess_MIME.py
index 0fc7f79..35baf41 100644
--- a/tests/Subprocess/test_Subprocess_MIME.py
+++ b/tests/Subprocess/test_Subprocess_MIME.py
@@ -142,6 +142,18 @@ def test_remote_image_does_exist(self):
         else:
             self.skipTest("Not online.")
 
+    def test_remote_image_does_exist_uppercase(self):
+        if self.isOnline:
+            path = os.path.join(self.examineDir, "remoteImageDoesExistUppercase.pdf")
+            self.addHeaders()
+            self.attachHTML('<img src="' + self.EXIST_IMG_UPPERCASE + '">')
+            (rc, output, error) = self.invokeAsSubprocess(outputFile=path)
+            self.assertEqual(0, rc)
+            self.assertEqual('', error)
+            self.assertTrue(os.path.exists(path))
+        else:
+            self.skipTest("Not online.")
+
     def test_non_embedded_image_jpeg(self):
         self.addHeaders()
         self.attachText("Hello!")
diff --git a/tests/UPPERCASE.png b/tests/UPPERCASE.png
new file mode 100644
index 0000000..cd7e50f
Binary files /dev/null and b/tests/UPPERCASE.png differ