diff --git a/tools/sigma/sigmac.py b/tools/sigma/sigmac.py
index 5a382b500..05f12299c 100755
--- a/tools/sigma/sigmac.py
+++ b/tools/sigma/sigmac.py
@@ -277,7 +277,7 @@ def main():
             if nb_result == 0: # backend get only 1 output
                 if not fileprefix == None: # want a prefix anyway
                     try:
-                        filename = "%s%s_nono_output%s" % (fileprefix,cmdargs.target,filename_ext)
+                        filename = "%s%s_mono_output%s" % (fileprefix,cmdargs.target,filename_ext)
                         out = open(filename, "w", encoding='utf-8')
                         fileprefix = None  # no need to open the same file many time
                     except (IOError, OSError) as e: