diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,11 @@
 
 pandoc-pyplot uses [Semantic Versioning](http://semver.org/spec/v2.0.0.html)
 
+Release 2.1.1.1
+---------------
+
+* Fixed a critical bug where pandoc-pyplot would interpret input from pandoc as a malformed command-line flag.
+
 Release 2.1.1.0
 ---------------
 
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -4,6 +4,12 @@
 
 `pandoc-pyplot` turns Python code present in your documents into embedded Matplotlib figures.
 
+* [Usage](#usage)
+* [Features](#features)
+* [Installation](#installation)
+* [Running the filter](#running-the-filter)
+* [Usage as a Haskell library](#usage-as-a-haskell-library)
+
 ## Usage
 
 The filter recognizes code blocks with the `.pyplot` class present. It will run the script in the associated code block in a Python interpreter and capture the generated Matplotlib figure.
@@ -120,7 +126,7 @@
 
 *New in version 2.1.0.0*
 
-To avoid repetition, `pandoc-pyplot` can be configured using simple YAML syntax. `pandoc-pyplot` will look for a `pandoc-pyplot.yml` file in the current working directory:
+To avoid repetition, `pandoc-pyplot` can be configured using simple YAML syntax. `pandoc-pyplot` will look for a `.pandoc-pyplot.yml` file in the current working directory:
 
 ```yaml
 # You can specify any or all of the following parameters
@@ -134,6 +140,7 @@
 These values override the default values, which are equivalent to:
 
 ```yaml
+# Defaults if no configuration is provided.
 interpreter: python
 directory: generated/
 format: png
diff --git a/executable/Main.hs b/executable/Main.hs
--- a/executable/Main.hs
+++ b/executable/Main.hs
@@ -37,12 +37,11 @@
 
 parseFlag :: [String] -> Maybe Flag
 parseFlag s
-    | null s                               = Nothing 
     | head s `elem` ["-h", "--help"]       = Just Help
     | head s `elem` ["-v", "--version"]    = Just Version
     | head s `elem` ["-f", "--formats"]    = Just Formats
     | head s `elem` ["-m", "--manual"]     = Just Manual
-    | otherwise                            = Just InvalidFlag
+    | otherwise                            = Nothing -- This is the regular input from pandoc
 
 flagAction :: Flag -> IO ()
 flagAction f
diff --git a/pandoc-pyplot.cabal b/pandoc-pyplot.cabal
--- a/pandoc-pyplot.cabal
+++ b/pandoc-pyplot.cabal
@@ -1,5 +1,5 @@
 name:           pandoc-pyplot
-version:        2.1.1.0
+version:        2.1.1.1
 cabal-version:  >= 1.12
 synopsis:       A Pandoc filter to include figures generated from Python code blocks
 description:    A Pandoc filter to include figures generated from Python code blocks. Keep the document and Python code in the same location. Output from Matplotlib is captured and included as a figure.