diff --git a/reftable/basics.c b/reftable/basics.c
index 2c5f34b39e..fea711db7e 100644
--- a/reftable/basics.c
+++ b/reftable/basics.c
@@ -39,8 +39,11 @@ size_t binsearch(size_t sz, int (*f)(size_t k, void *args), void *args)
 	 */
 	while (hi - lo > 1) {
 		size_t mid = lo + (hi - lo) / 2;
+		int ret = f(mid, args);
+		if (ret < 0)
+			return sz;
 
-		if (f(mid, args))
+		if (ret > 0)
 			hi = mid;
 		else
 			lo = mid;
diff --git a/reftable/basics.h b/reftable/basics.h
index 2672520e76..523ecd5307 100644
--- a/reftable/basics.h
+++ b/reftable/basics.h
@@ -22,8 +22,9 @@ uint32_t get_be24(uint8_t *in);
 void put_be16(uint8_t *out, uint16_t i);
 
 /*
- * find smallest index i in [0, sz) at which f(i) is true, assuming
- * that f is ascending. Return sz if f(i) is false for all indices.
+ * find smallest index i in [0, sz) at which `f(i) > 0`, assuming that f is
+ * ascending. Return sz if `f(i) == 0` for all indices. The search is aborted
+ * and `sz` is returned in case `f(i) < 0`.
  *
  * Contrary to bsearch(3), this returns something useful if the argument is not
  * found.
diff --git a/reftable/block.c b/reftable/block.c
index 57e3dbf658..ca217636ae 100644
--- a/reftable/block.c
+++ b/reftable/block.c
@@ -387,11 +387,6 @@ int block_reader_seek(struct block_reader *br, struct block_iter *it,
 	int err = 0;
 	size_t i;
 
-	if (args.error) {
-		err = REFTABLE_FORMAT_ERROR;
-		goto done;
-	}
-
 	/*
 	 * Perform a binary search over the block's restart points, which
 	 * avoids doing a linear scan over the whole block. Like this, we
@@ -405,6 +400,10 @@ int block_reader_seek(struct block_reader *br, struct block_iter *it,
 	 * too many record.
 	 */
 	i = binsearch(br->restart_count, &restart_needle_less, &args);
+	if (args.error) {
+		err = REFTABLE_FORMAT_ERROR;
+		goto done;
+	}
 
 	/*
 	 * Now there are multiple cases: