diff -r aa77f7eb2bf1 Doc/library/json.rst
--- a/Doc/library/json.rst	Mon Feb 18 13:33:37 2013 +0200
+++ b/Doc/library/json.rst	Mon Feb 18 18:43:00 2013 +0200
@@ -101,7 +101,7 @@
         "json": "obj"
     }
     $ echo '{1.2:3.4}' | python -mjson.tool
-    Expecting property name enclosed in double quotes: line 1 column 1 (char 1)
+    Expecting property name enclosed in double quotes: line 1 column 2 (char 1)
 
 .. highlight:: python3
 
diff -r aa77f7eb2bf1 Lib/json/__init__.py
--- a/Lib/json/__init__.py	Mon Feb 18 13:33:37 2013 +0200
+++ b/Lib/json/__init__.py	Mon Feb 18 18:43:00 2013 +0200
@@ -96,7 +96,7 @@
         "json": "obj"
     }
     $ echo '{ 1.2:3.4}' | python -m json.tool
-    Expecting property name enclosed in double quotes: line 1 column 2 (char 2)
+    Expecting property name enclosed in double quotes: line 1 column 3 (char 2)
 """
 __version__ = '2.0.9'
 __all__ = [
diff -r aa77f7eb2bf1 Lib/json/decoder.py
--- a/Lib/json/decoder.py	Mon Feb 18 13:33:37 2013 +0200
+++ b/Lib/json/decoder.py	Mon Feb 18 18:43:00 2013 +0200
@@ -24,7 +24,7 @@
         newline = '\n'
     lineno = doc.count(newline, 0, pos) + 1
     if lineno == 1:
-        colno = pos
+        colno = pos + 1
     else:
         colno = pos - doc.rindex(newline, 0, pos)
     return lineno, colno
diff -r aa77f7eb2bf1 Lib/json/tool.py
--- a/Lib/json/tool.py	Mon Feb 18 13:33:37 2013 +0200
+++ b/Lib/json/tool.py	Mon Feb 18 18:43:00 2013 +0200
@@ -7,7 +7,7 @@
         "json": "obj"
     }
     $ echo '{ 1.2:3.4}' | python -m json.tool
-    Expecting property name enclosed in double quotes: line 1 column 2 (char 2)
+    Expecting property name enclosed in double quotes: line 1 column 3 (char 2)
 
 """
 import sys
diff -r aa77f7eb2bf1 Lib/test/json_tests/test_fail.py
--- a/Lib/test/json_tests/test_fail.py	Mon Feb 18 13:33:37 2013 +0200
+++ b/Lib/test/json_tests/test_fail.py	Mon Feb 18 18:43:00 2013 +0200
@@ -125,8 +125,8 @@
         ]
         for data, msg, idx in test_cases:
             self.assertRaisesRegex(ValueError,
-                r'^{0}: line 1 column {1} \(char {1}\)'.format(
-                    re.escape(msg), idx),
+                r'^{0}: line 1 column {1} \(char {2}\)'.format(
+                    re.escape(msg), idx + 1, idx),
                 self.loads, data)
 
     def test_unexpected_data(self):
@@ -155,8 +155,8 @@
         ]
         for data, msg, idx in test_cases:
             self.assertRaisesRegex(ValueError,
-                r'^{0}: line 1 column {1} \(char {1}\)'.format(
-                    re.escape(msg), idx),
+                r'^{0}: line 1 column {1} \(char {2}\)'.format(
+                    re.escape(msg), idx + 1, idx),
                 self.loads, data)
 
     def test_extra_data(self):
@@ -173,10 +173,22 @@
         for data, msg, idx in test_cases:
             self.assertRaisesRegex(ValueError,
                 r'^{0}: line 1 column {1} - line 1 column {2}'
-                r' \(char {1} - {2}\)'.format(
-                    re.escape(msg), idx, len(data)),
+                r' \(char {3} - {4}\)'.format(
+                    re.escape(msg), idx + 1, len(data) + 1, idx, len(data)),
                 self.loads, data)
 
+    def test_multiline(self):
+        test_cases = [
+            ('!', 'Expecting value', 1, 1, 0),
+            (' !', 'Expecting value', 1, 2, 1),
+            ('\n!', 'Expecting value', 2, 1, 1),
+            ('\n  \n\n     !', 'Expecting value', 4, 6, 10),
+        ]
+        for data, msg, line, col, idx in test_cases:
+            self.assertRaisesRegex(ValueError,
+                r'^{0}: line {1} column {2} \(char {3}\)$'.format(
+                    re.escape(msg), line, col, idx),
+                self.loads, data)
 
 class TestPyFail(TestFail, PyTest): pass
 class TestCFail(TestFail, CTest): pass
diff -r aa77f7eb2bf1 Misc/NEWS
--- a/Misc/NEWS	Mon Feb 18 13:33:37 2013 +0200
+++ b/Misc/NEWS	Mon Feb 18 18:43:00 2013 +0200
@@ -257,6 +257,9 @@
 Library
 -------
 
+- Issue #17225: JSON decoder now counts columns in the first line starting
+  with 1, as in other lines.
+
 - Issue #13153: Tkinter functions now raise TclError instead of ValueError when
   a string argument contains non-BMP character.