diff -r 628bd1ebfa22 Lib/idlelib/IOBinding.py
--- a/Lib/idlelib/IOBinding.py	Fri Mar 18 03:03:10 2016 +0000
+++ b/Lib/idlelib/IOBinding.py	Thu Mar 17 13:49:41 2016 +0200
@@ -62,7 +62,7 @@ locale_encoding = locale_encoding.lower(
 encoding = locale_encoding  ### KBK 07Sep07  This is used all over IDLE, check!
                             ### 'encoding' is used below in encode(), check!
 
-coding_re = re.compile(r'^[ \t\f]*#.*coding[:=][ \t]*([-\w.]+)', re.ASCII)
+coding_re = re.compile(r'^[ \t\f]*#.*?coding[:=][ \t]*([-\w.]+)', re.ASCII)
 blank_re = re.compile(r'^[ \t\f]*(?:[#\r\n]|$)', re.ASCII)
 
 def coding_spec(data):
diff -r 628bd1ebfa22 Lib/lib2to3/pgen2/tokenize.py
--- a/Lib/lib2to3/pgen2/tokenize.py	Fri Mar 18 03:03:10 2016 +0000
+++ b/Lib/lib2to3/pgen2/tokenize.py	Thu Mar 17 13:49:41 2016 +0200
@@ -236,7 +236,7 @@ class Untokenizer:
                 startline = False
             toks_append(tokval)
 
-cookie_re = re.compile(r'^[ \t\f]*#.*coding[:=][ \t]*([-\w.]+)', re.ASCII)
+cookie_re = re.compile(r'^[ \t\f]*#.*?coding[:=][ \t]*([-\w.]+)', re.ASCII)
 blank_re = re.compile(br'^[ \t\f]*(?:[#\r\n]|$)', re.ASCII)
 
 def _get_normal_name(orig_enc):
diff -r 628bd1ebfa22 Lib/test/test_importlib/source/test_source_encoding.py
--- a/Lib/test/test_importlib/source/test_source_encoding.py	Fri Mar 18 03:03:10 2016 +0000
+++ b/Lib/test/test_importlib/source/test_source_encoding.py	Thu Mar 17 13:49:41 2016 +0200
@@ -14,7 +14,7 @@ import unittest
 import warnings
 
 
-CODING_RE = re.compile(r'^[ \t\f]*#.*coding[:=][ \t]*([-\w.]+)', re.ASCII)
+CODING_RE = re.compile(r'^[ \t\f]*#.*?coding[:=][ \t]*([-\w.]+)', re.ASCII)
 
 
 class EncodingTest:
diff -r 628bd1ebfa22 Lib/test/test_source_encoding.py
--- a/Lib/test/test_source_encoding.py	Fri Mar 18 03:03:10 2016 +0000
+++ b/Lib/test/test_source_encoding.py	Thu Mar 17 13:49:41 2016 +0200
@@ -1,11 +1,12 @@
 # -*- coding: koi8-r -*-
 
 import unittest
-from test.support import TESTFN, unlink, unload, rmtree
+from test.support import TESTFN, unlink, unload, rmtree, script_helper, captured_stdout
 import importlib
 import os
 import sys
 import subprocess
+import tempfile
 
 class SourceEncodingTest(unittest.TestCase):
 
@@ -142,5 +143,64 @@ class SourceEncodingTest(unittest.TestCa
                         msg=c.exception.args[0])
 
 
+class AbstractSourceEncodingTest:
+
+    def test_first_coding_line(self):
+        src = (b'#coding:iso8859-15\n'
+               b'print(ascii("\xc3\xa4"))\n')
+        out = self.run_script(src)
+        self.assertEqual(out.rstrip(), br"'\xc3\u20ac'")
+
+    def test_second_coding_line(self):
+        src = (b'#\n'
+               b'#coding:iso8859-15\n'
+               b'print(ascii("\xc3\xa4"))\n')
+        out = self.run_script(src)
+        self.assertEqual(out.rstrip(), br"'\xc3\u20ac'")
+
+    def test_double_coding_same_line(self):
+        src = (b'#coding:iso8859-15 coding:latin1\n'
+               b'print(ascii("\xc3\xa4"))\n')
+        out = self.run_script(src)
+        self.assertEqual(out.rstrip(), br"'\xc3\u20ac'")
+
+    def test_double_coding_line(self):
+        src = (b'#coding:iso8859-15\n'
+               b'#coding:latin1\n'
+               b'print(ascii("\xc3\xa4"))\n')
+        out = self.run_script(src)
+        self.assertEqual(out.rstrip(), br"'\xc3\u20ac'")
+
+    def test_first_non_utf8_coding_line(self):
+        src = (b'#coding:iso-8859-15 \xa4\n'
+               b'print(ascii("\xc3\xa4"))\n')
+        out = self.run_script(src)
+        self.assertEqual(out.rstrip(), br"'\xc3\u20ac'")
+
+    def test_second_non_utf8_coding_line(self):
+        src = (b'\n'
+               b'#coding:iso-8859-15 \xa4\n'
+               b'print(ascii("\xc3\xa4"))\n')
+        out = self.run_script(src)
+        self.assertEqual(out.rstrip(), br"'\xc3\u20ac'")
+
+class StringSourceEncodingTest(AbstractSourceEncodingTest, unittest.TestCase):
+
+    def run_script(self, src):
+        with captured_stdout() as stdout:
+            exec(src)
+        return stdout.getvalue().encode()
+
+class FileSourceEncodingTest(AbstractSourceEncodingTest, unittest.TestCase):
+
+    def run_script(self, src):
+        with tempfile.TemporaryDirectory() as tmpd:
+            fn = os.path.join(tmpd, "test.py")
+            with open(fn, "wb") as fp:
+                fp.write(src)
+            res = script_helper.assert_python_ok(fn)
+        return res.out
+
+
 if __name__ == "__main__":
     unittest.main()
diff -r 628bd1ebfa22 Lib/tokenize.py
--- a/Lib/tokenize.py	Fri Mar 18 03:03:10 2016 +0000
+++ b/Lib/tokenize.py	Thu Mar 17 13:49:41 2016 +0200
@@ -34,7 +34,7 @@ import re
 import sys
 from token import *
 
-cookie_re = re.compile(r'^[ \t\f]*#.*coding[:=][ \t]*([-\w.]+)', re.ASCII)
+cookie_re = re.compile(r'^[ \t\f]*#.*?coding[:=][ \t]*([-\w.]+)', re.ASCII)
 blank_re = re.compile(br'^[ \t\f]*(?:[#\r\n]|$)', re.ASCII)
 
 import token
diff -r 628bd1ebfa22 Parser/tokenizer.c
--- a/Parser/tokenizer.c	Fri Mar 18 03:03:10 2016 +0000
+++ b/Parser/tokenizer.c	Thu Mar 17 13:49:41 2016 +0200
@@ -275,6 +275,7 @@ get_coding_spec(const char *s, char **sp
                         return 0;
                 }
                 *spec = r;
+                break;
             }
         }
     }
diff -r 628bd1ebfa22 Tools/scripts/findnocoding.py
--- a/Tools/scripts/findnocoding.py	Fri Mar 18 03:03:10 2016 +0000
+++ b/Tools/scripts/findnocoding.py	Thu Mar 17 13:49:41 2016 +0200
@@ -32,7 +32,7 @@ except ImportError:
                          "no sophisticated Python source file search will be done.", file=sys.stderr)
 
 
-decl_re = re.compile(rb'^[ \t\f]*#.*coding[:=][ \t]*([-\w.]+)')
+decl_re = re.compile(rb'^[ \t\f]*#.*?coding[:=][ \t]*([-\w.]+)')
 blank_re = re.compile(rb'^[ \t\f]*(?:[#\r\n]|$)')
 
 def get_declaration(line):