diff --git a/src/test/test_oom.c b/src/test/test_oom.c
index ad590b8434..973501c3d7 100644
--- a/src/test/test_oom.c
+++ b/src/test/test_oom.c
@@ -222,7 +222,6 @@ test_oom_streambuf(void *arg)
   tt_int_op(buf_get_total_allocation(), OP_EQ, 0);
 
   monotime_coarse_set_mock_time_nsec(start_ns);
-  const uint32_t ts_start = monotime_coarse_get_stamp();
 
   /* Start all circuits with a bit of data queued in cells */
 
@@ -272,23 +271,27 @@ test_oom_streambuf(void *arg)
   now_ns += 1000000000;
   monotime_coarse_set_mock_time_nsec(now_ns);
   tvts = monotime_coarse_get_stamp();
-  const uint32_t diff = tvts - ts_start;
-  printf("\n!!!! %u\n", (unsigned) diff);
 
-  tt_int_op(circuit_max_queued_cell_age(c1, tvts), OP_EQ, 500);
-  tt_int_op(circuit_max_queued_cell_age(c2, tvts), OP_EQ, 490);
-  tt_int_op(circuit_max_queued_cell_age(c3, tvts), OP_EQ, 480);
-  tt_int_op(circuit_max_queued_cell_age(c4, tvts), OP_EQ, 0);
+#define ts_is_approx(ts, val) do {                                   \
+    uint32_t x_ = (uint32_t) monotime_coarse_stamp_units_to_approx_msec(ts); \
+    tt_int_op(x_, OP_GE, val - 5);                                      \
+    tt_int_op(x_, OP_LE, val + 5);                                      \
+  } while (0)
 
-  tt_int_op(circuit_max_queued_data_age(c1, tvts), OP_EQ, 390);
-  tt_int_op(circuit_max_queued_data_age(c2, tvts), OP_EQ, 380);
-  tt_int_op(circuit_max_queued_data_age(c3, tvts), OP_EQ, 0);
-  tt_int_op(circuit_max_queued_data_age(c4, tvts), OP_EQ, 370);
+  ts_is_approx(circuit_max_queued_cell_age(c1, tvts), 500);
+  ts_is_approx(circuit_max_queued_cell_age(c2, tvts), 490);
+  ts_is_approx(circuit_max_queued_cell_age(c3, tvts), 480);
+  ts_is_approx(circuit_max_queued_cell_age(c4, tvts), 0);
 
-  tt_int_op(circuit_max_queued_item_age(c1, tvts), OP_EQ, 500);
-  tt_int_op(circuit_max_queued_item_age(c2, tvts), OP_EQ, 490);
-  tt_int_op(circuit_max_queued_item_age(c3, tvts), OP_EQ, 480);
-  tt_int_op(circuit_max_queued_item_age(c4, tvts), OP_EQ, 370);
+  ts_is_approx(circuit_max_queued_data_age(c1, tvts), 390);
+  ts_is_approx(circuit_max_queued_data_age(c2, tvts), 380);
+  ts_is_approx(circuit_max_queued_data_age(c3, tvts), 0);
+  ts_is_approx(circuit_max_queued_data_age(c4, tvts), 370);
+
+  ts_is_approx(circuit_max_queued_item_age(c1, tvts), 500);
+  ts_is_approx(circuit_max_queued_item_age(c2, tvts), 490);
+  ts_is_approx(circuit_max_queued_item_age(c3, tvts), 480);
+  ts_is_approx(circuit_max_queued_item_age(c4, tvts), 370);
 
   tt_int_op(cell_queues_get_total_allocation(), OP_EQ,
             packed_cell_mem_cost() * 80);
@@ -304,7 +307,7 @@ test_oom_streambuf(void *arg)
     smartlist_add(edgeconns, ec);
   }
   tt_int_op(buf_get_total_allocation(), OP_EQ, 4096*17*2);
-  tt_int_op(circuit_max_queued_item_age(c4, tvts), OP_EQ, 1000);
+  ts_is_approx(circuit_max_queued_item_age(c4, tvts), 1000);
 
   tt_int_op(cell_queues_check_size(), OP_EQ, 0);