diff --git a/README b/README
index 22c2dd6..e94962f 100644
--- a/README
+++ b/README
@@ -7,7 +7,7 @@ It allows arithmetic operations between them and conversions from and
 to different units.
 
 It is distributed with a comprehensive list of physical units, prefixes
-and constants. Due to it's modular design, you to extend (or even rewrite!)
+and constants. Due to its modular design, you to extend (or even rewrite!)
 the complete list without changing the source code.
 
 It has a complete test coverage. It runs in Python 2.7 and 3.X
diff --git a/docs/index.rst b/docs/index.rst
index bb14dca..39682eb 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -9,7 +9,7 @@ Pint: a Python units library
 
 Pint is Python package to define, operate and manipulate **physical quantities**: the product of a numerical value and a unit of measurement. It allows arithmetic operations between them and conversions from and to different units.
 
-It is distributed with a comprehensive list of physical units, prefixes and constants. Due to it's modular design, you can extend (or even rewrite!) the complete list without changing the source code.
+It is distributed with a comprehensive list of physical units, prefixes and constants. Due to its modular design, you can extend (or even rewrite!) the complete list without changing the source code.
 
 It has a complete test coverage. It runs in Python 2.6+ and 3.2+ with no other dependency. It licensed under BSD.
 
@@ -37,7 +37,7 @@ Extended conversion flags are given to provide symbolic, latex and pretty format
 
 **Small codebase**: easy to maintain codebase with a flat hierarchy.
 
-**Dependency free**: it depends only on Python and it's standard library.
+**Dependency free**: it depends only on Python and its standard library.
 
 **Python 2 and 3**: a single codebase that runs unchanged in Python 2.7+ and Python 3.0+.
 
diff --git a/docs/tutorial.rst b/docs/tutorial.rst
index a82765b..ccfe0f1 100644
--- a/docs/tutorial.rst
+++ b/docs/tutorial.rst
@@ -74,7 +74,7 @@ If you want to convert in-place (i.e. without creating another object), you can
    >>> print(speed)
    7086.614173228345 inch / minute
 
-If you ask Pint to perform and invalid conversion:
+If you ask Pint to perform an invalid conversion:
 
 .. doctest::
 
diff --git a/pint/unit.py b/pint/unit.py
index 6bb043e..21ad20f 100644
--- a/pint/unit.py
+++ b/pint/unit.py
@@ -614,7 +614,7 @@ class UnitRegistry(object):
             >>> with ureg.context('one'):
             ...     pass
 
-        If the context has an argument, you can specify it's value as a keyword
+        If the context has an argument, you can specify its value as a keyword
         argument::
 
             >>> with ureg.context('one', n=1):