diff --git a/common/python/nomadcore/parser_backend.py b/common/python/nomadcore/parser_backend.py
index 86dbe37e0fb125c8e86f58826199285ecc2c8da0..9d977965cd11d57ea9422a49bddbf7d02584ce3d 100644
--- a/common/python/nomadcore/parser_backend.py
+++ b/common/python/nomadcore/parser_backend.py
@@ -245,7 +245,7 @@ class JsonParseEventsWriterBackend(object):
             'fInLineNr': match_telemetry['fInLineNr'],
             'matcherName': match_telemetry['matcherName'],
             'matchFlags': match_telemetry['matchFlags'],
-            'flatValues': match_telemetry['span_flat'],
+            'matchSpansFlat': match_telemetry['matchSpansFlat'],
             'matcherGroup': match_telemetry['matcherGroup'],
         }
         self.__jsonOutput(res)
diff --git a/common/python/nomadcore/simple_parser.py b/common/python/nomadcore/simple_parser.py
index bba15465022af09df3fd5d66ee3210bede0082fb..54cb1fd1f029bb1c811d1a7b46fc69a6842ca5f3 100644
--- a/common/python/nomadcore/simple_parser.py
+++ b/common/python/nomadcore/simple_parser.py
@@ -753,7 +753,7 @@ class CompiledMatcher(object):
             span_flat.append(len(g))
             for s in g:
                 span_flat.extend(s)
-        result['span_flat'] = span_flat
+        result['matchSpansFlat'] = span_flat
         result['matchFlags'] = (
             result['match'] | (result['coverageIgnore'] << 2) |
             targetStartEnd << 5 | int(result['matcher_does_nothing'] and result['match']) << 6)