diff --git a/furl/furl.py b/furl/furl.py
index cd6d710..c2f5c08 100644
--- a/furl/furl.py
+++ b/furl/furl.py
@@ -223,9 +223,11 @@ def is_valid_encoded_query_value(value):
     return is_valid_encoded_query_value.regex.match(value) is not None
 
 
-@static_vars(regex=re.compile(r'[a-zA-Z][a-zA-Z\-\.\+]*'))
+@static_vars(regex=re.compile(r'[a-zA-Z][a-zA-Z0-9\-\.\+]*'))
 def is_valid_scheme(scheme):
-    return is_valid_scheme.regex.match(scheme) is not None
+    if is_valid_scheme.regex.match(scheme) is None:
+        return False
+    return is_valid_scheme.regex.match(scheme).group() == scheme
 
 
 @static_vars(regex=re.compile('[%s]' % re.escape(INVALID_HOST_CHARS)))
@@ -1423,6 +1425,9 @@ def scheme(self):
     def scheme(self, scheme):
         if callable_attr(scheme, 'lower'):
             scheme = scheme.lower()
+        if scheme:
+            if not is_valid_scheme(scheme):
+                raise ValueError("Invalid Scheme")
         self._scheme = scheme
 
     @property
diff --git a/tests/test_furl.py b/tests/test_furl.py
index bc268c8..4fa9f2d 100644
--- a/tests/test_furl.py
+++ b/tests/test_furl.py
@@ -1630,6 +1630,16 @@ def test_odd_urls(self):
         assert f.netloc == '' and str(f.path) == '//path'
         assert f.url == '////path'
 
+        # Check that schemes with invalid characters are rejected
+        f = furl.furl('sch^eme://user@host.com/path')
+        assert f.scheme is None
+
+        f = furl.furl('sch2323eme://user@host.com/path')
+        assert f.scheme == 'sch2323eme'
+        assert f.username == 'user'
+        assert f.host == 'host.com'
+
+
         # TODO(grun): Test more odd URLs.
 
     def test_hosts(self):