diff --git a/bilby/gw/likelihood.py b/bilby/gw/likelihood.py
index cfbcf53c10fec924d961c3745ede8c0486c8d3b2..d75251eddc7aa8e94aa3a1386d5df682ce76ce3f 100644
--- a/bilby/gw/likelihood.py
+++ b/bilby/gw/likelihood.py
@@ -986,7 +986,9 @@ class ROQGravitationalWaveTransient(GravitationalWaveTransient):
                 linear_matrix[roq_idxs],
                 max_elements) * 4 / ifo.strain_data.duration
 
-            del tc_shifted_data
+            del tc_shifted_data, shifted_data, single_time_shift, overlap_frequencies
+            import gc
+            gc.collect()
 
             self.weights[ifo.name + '_quadratic'] = build_roq_weights(
                 1 /