diff --git a/check_matrix_synapse.py b/check_matrix_synapse.py
index 3643c14..c57ff5b 100755
--- a/check_matrix_synapse.py
+++ b/check_matrix_synapse.py
@@ -34,7 +34,7 @@ def main():
                 print(f"UNKNOWN: no data for average GC time")
                 sys.exit(nagios.UNKNOWN)
 
-            python_gc_time_sum = np.round(np.average(), 5)
+            python_gc_time_sum = np.round(np.average(raw_gc_time), 5)
             if python_gc_time_sum >= python_gc_time_sum_MAX:
                 print(f"CRITICAL: average GC time per collection is {python_gc_time_sum} sec. |'garbage-collection'={python_gc_time_sum}s;;;")
                 sys.exit(nagios.CRITICAL)