diff --git a/gradint-build/src/synth.py b/gradint-build/src/synth.py
index c8d3840c772d16f9a10dcc403eedbc60fc42e17e..2d5f1dc565d9c6241a27bd72970ef49c6ed780b5 100644
--- a/gradint-build/src/synth.py
+++ b/gradint-build/src/synth.py
@@ -767,7 +767,7 @@ class GeneralFileSynth(Synth):
     def makefile(self,lang,text):
         for l,c,f in extra_speech_tofile:
             if l==lang:
-                os.system(c % shell_escape(text))
+                if os.system(c % shell_escape(text)): raise Exception("Your extra_speech_tofile command failed")
                 fname = os.tempnam()+extsep+soundFileType(f)
                 if unix: os.system('mv "'+f+'" "'+fname+'"') # because os.rename() can throw an exception if renaming cross-device on some systems
                 else: os.rename(f,fname)