diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 pandoc-plot uses [Semantic Versioning](http://semver.org/spec/v2.0.0.html)
 
+## Release 1.5.3
+
+* Fixed an issue where the `tight_bbox` option for Matplotlib plots was ignored (#48)
+
 ## Release 1.5.2
 
 * Overhauled the way executables are handled. This fixes an issue where executables specified in documents (rather than configuration) were ignored (#46).
diff --git a/pandoc-plot.cabal b/pandoc-plot.cabal
--- a/pandoc-plot.cabal
+++ b/pandoc-plot.cabal
@@ -1,6 +1,6 @@
 cabal-version:  2.2
 name:           pandoc-plot
-version:        1.5.2
+version:        1.5.3
 synopsis:       A Pandoc filter to include figures generated from code blocks using your plotting toolkit of choice.
 description:    A Pandoc filter to include figures generated from code blocks. 
                 Keep the document and code in the same location. Output is 
diff --git a/src/Text/Pandoc/Filter/Plot/Renderers.hs b/src/Text/Pandoc/Filter/Plot/Renderers.hs
--- a/src/Text/Pandoc/Filter/Plot/Renderers.hs
+++ b/src/Text/Pandoc/Filter/Plot/Renderers.hs
@@ -120,7 +120,9 @@
 -- | Parse code block headers for extra attributes that are specific
 -- to this renderer. By default, no extra attributes are parsed.
 parseExtraAttrs :: Toolkit -> Map Text Text -> Map Text Text
-parseExtraAttrs Matplotlib = M.filterWithKey (\k _ -> k `elem` ["tight_bbox", "transparent"])
+parseExtraAttrs Matplotlib = M.filterWithKey (\k _ -> k `elem` [ pack $ show MatplotlibTightBBoxK
+                                                               , pack $ show MatplotlibTransparentK
+                                                               ])
 parseExtraAttrs _ = return mempty
 
 -- | List of toolkits available on this machine.
diff --git a/src/Text/Pandoc/Filter/Plot/Renderers/Matplotlib.hs b/src/Text/Pandoc/Filter/Plot/Renderers/Matplotlib.hs
--- a/src/Text/Pandoc/Filter/Plot/Renderers/Matplotlib.hs
+++ b/src/Text/Pandoc/Filter/Plot/Renderers/Matplotlib.hs
@@ -60,8 +60,8 @@
 |]
   where
     attrs = M.fromList extraAttrs
-    tight_ = readBool $ M.findWithDefault "False" "tight" attrs
-    transparent_ = readBool $ M.findWithDefault "False" "transparent" attrs
+    tight_ = readBool $ M.findWithDefault "False" (T.pack $ show MatplotlibTightBBoxK) attrs
+    transparent_ = readBool $ M.findWithDefault "False" (T.pack $ show MatplotlibTransparentK) attrs
     tightBox = if tight_ then ("'tight'" :: Text) else ("None" :: Text)
     transparent = if transparent_ then ("True" :: Text) else ("False" :: Text)