diff --git a/conf/modules.config b/conf/modules.config
index 8f291cfe..5363c64d 100644
--- a/conf/modules.config
+++ b/conf/modules.config
@@ -242,6 +242,7 @@ process {
     }
 
     withName: 'OPENMS_IDMASSACCURACY' {
+        ext.prefix  = {"${meta.spectra}"}
         ext.args    = [
             (params.precursor_error_units == 'ppm') ? "-precursor_error_ppm": "",
             "-fragment_mass_tolerance ${params.fragment_mass_tolerance}"