diff --git a/src/pattern.c b/src/pattern.c
index 4a3fe29..e028545 100644
--- a/src/pattern.c
+++ b/src/pattern.c
@@ -2101,6 +2101,10 @@
 		HA_RWLOCK_WRUNLOCK(PATEXP_LOCK, &expr->lock);
 	}
 	HA_SPIN_UNLOCK(PATREF_LOCK, &ref->lock);
+
+#if defined(HA_HAVE_MALLOC_TRIM)
+	malloc_trim(0);
+#endif
 }
 
 /* This function prunes all entries of <ref>. This function