diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+1.2.1.0
+=======
+
+* Execute `haskintex` with `-werror` flag.
+
 1.2.0.0
 =======
 
diff --git a/pdf-slave.cabal b/pdf-slave.cabal
--- a/pdf-slave.cabal
+++ b/pdf-slave.cabal
@@ -1,5 +1,5 @@
 name:                pdf-slave
-version:             1.2.0.0
+version:             1.2.1.0
 synopsis:            Tool to generate PDF from haskintex templates and YAML input
 description:         Please see README.md
 homepage:            https://github.com/NCrashed/pdf-slave#readme
diff --git a/src/Text/PDF/Slave/Render.hs b/src/Text/PDF/Slave/Render.hs
--- a/src/Text/PDF/Slave/Render.hs
+++ b/src/Text/PDF/Slave/Render.hs
@@ -181,6 +181,7 @@
       haskintex = bash "haskintex" $ [
           "-overwrite"
         , "-verbose"
+        , "-werror"
         , toTextArg $ baseDir </> bodyName ]
         ++ templateFileHaskintexOpts
   -- input file might be missing, if missing we can inject input from parent