diff --git a/builders/builder.py b/builders/builder.py
index b0a0c54..6c13e40 100644
--- a/builders/builder.py
+++ b/builders/builder.py
@@ -84,7 +84,7 @@ class Builder(object):
         if self.args.verbose:
             self._print(text, *args)
 
-    def _run_command(self, cmd, err_msg):
+    def _run_command(self, cmd, err_msg, exit_code=0):
         """
         Run command in subprocess and print error message in case of Exception.
 
@@ -93,7 +93,7 @@ class Builder(object):
         proc = Popen(cmd, stdout=PIPE, stderr=PIPE, universal_newlines=True)
         output, error = proc.communicate()
         code = proc.wait()
-        if code != 0:
+        if code != exit_code:
             self._print(output)
             self._print(error)
             raise Exception(err_msg)
diff --git a/builders/windows-builder.py b/builders/windows-builder.py
index 8153f17..9c85636 100644
--- a/builders/windows-builder.py
+++ b/builders/windows-builder.py
@@ -320,7 +320,7 @@ class WindowsBuilder(Builder):
         """
         self._print('Running HTML Help Workshop...')
         os.chdir(os.path.join(self.manual_build_path, 'htmlhelp'))
-        self._run_command([self.htmlhelp_exe, 'OpenLP.chm'], 'Error running HTML Help Workshop')
+        self._run_command([self.htmlhelp_exe, 'OpenLP.chm'], 'Error running HTML Help Workshop', exit_code=1)
 
     def build_package(self):
         """