diff --git a/plugins/askrene/refine.c b/plugins/askrene/refine.c
index f790e00c0..d68027094 100644
--- a/plugins/askrene/refine.c
+++ b/plugins/askrene/refine.c
@@ -445,8 +445,18 @@ static bool increase_flows(const struct route_query *rq,
 			if (amount_msat_greater(capacity, ceiling[i]))
 				capacity = ceiling[i];
 
-			if (!amount_msat_sub(&remaining, capacity, flows[i]->delivers))
-				abort();
+			/* We've had a report that this subtract can fail:
+			 * that implies we've pushed a flow past its estimated
+			 * capacity.  That shouldn't happen, but if it does,
+			 * we don't crash */
+			if (!amount_msat_sub(&remaining, capacity, flows[i]->delivers)) {
+			        rq_log(rq, rq, LOG_BROKEN,
+				       "%s: flow %s delivers %s which is more than the path's capacity %s", __func__,
+				       fmt_flow_full(tmpctx, rq, flows[i]),
+				       fmt_amount_msat(tmpctx, flows[i]->delivers),
+				       fmt_amount_msat(tmpctx, capacity));
+				continue;
+			}
 			if (amount_msat_greater(remaining, best_remaining)) {
 				best_flownum = i;
 				best_remaining = remaining;