diff --git a/diagrams-pgf.cabal b/diagrams-pgf.cabal
--- a/diagrams-pgf.cabal
+++ b/diagrams-pgf.cabal
@@ -1,5 +1,5 @@
 name:                diagrams-pgf
-version:             1.4.2
+version:             1.4.2.1
 synopsis:            PGF backend for diagrams drawing EDSL.
 license:             BSD3
 license-file:        LICENSE
@@ -13,7 +13,7 @@
 cabal-version:       1.18
 extra-source-files:  README.md, diagrams/*.svg
 extra-doc-files:     diagrams/*.svg
-tested-with:         GHC ==8.4.4 || ==8.6.5 || ==8.8.4 || ==8.10.4 || ==9.0.1 || ==9.2.1
+tested-with:         GHC ==8.4.4 || ==8.6.5 || ==8.8.4 || ==8.10.7 || ==9.0.2 || ==9.2.7 || ==9.4.5 || ==9.6.1
 
 description:
   This package provides a modular backend for rendering diagrams created
@@ -34,7 +34,7 @@
     Graphics.Rendering.PGF
   hs-source-dirs:      src
   build-depends:
-    base                 >= 4.4   && < 4.17,
+    base                 >= 4.4   && < 4.19,
     bytestring           >= 0.9   && < 1.1,
     bytestring-builder               < 1.1,
     containers           >= 0.3   && < 0.7,
@@ -45,7 +45,7 @@
     filepath             >= 1.2   && < 1.5,
     hashable             >= 1.1   && < 1.5,
     mtl                  >= 2.1   && < 3.0,
-    optparse-applicative >= 0.13  && < 0.17,
+    optparse-applicative >= 0.13  && < 0.19,
     process              >= 1.0   && < 1.7,
     split                >= 0.1.2 && < 0.3,
     texrunner            <= 0.0.2,
diff --git a/src/Graphics/Rendering/PGF.hs b/src/Graphics/Rendering/PGF.hs
--- a/src/Graphics/Rendering/PGF.hs
+++ b/src/Graphics/Rendering/PGF.hs
@@ -93,6 +93,7 @@
 
 import           Codec.Compression.Zlib
 import           Codec.Picture
+import           Control.Monad                (when)
 import           Control.Monad.RWS
 import           Data.ByteString.Builder
 import           Data.ByteString.Char8        (ByteString)