diff --git a/Makefile b/Makefile
index 0e4b38eb..d9a2da63 100755
--- a/Makefile
+++ b/Makefile
@@ -17,7 +17,7 @@ else
 endif
 
 errfff:
-	f2py3 -c PyHEADTAIL/general/errfff.f90 -m errfff
+	f2py -c PyHEADTAIL/general/errfff.f -m errfff
 	mv errfff*.so PyHEADTAIL/general/
 
 clean:
diff --git a/PyHEADTAIL/general/errfff.f90 b/PyHEADTAIL/general/errfff.f
similarity index 100%
rename from PyHEADTAIL/general/errfff.f90
rename to PyHEADTAIL/general/errfff.f