diff --git a/storage/blockdevice/tests/TESTS/blockdevice/general_block_device/main.cpp b/storage/blockdevice/tests/TESTS/blockdevice/general_block_device/main.cpp
index 6ec35c5679..93e898d395 100644
--- a/storage/blockdevice/tests/TESTS/blockdevice/general_block_device/main.cpp
+++ b/storage/blockdevice/tests/TESTS/blockdevice/general_block_device/main.cpp
@@ -549,8 +549,15 @@ void test_contiguous_erase_write_read()
     utest_printf("contiguous_erase_size=0x%" PRIx64 "\n", contiguous_erase_size);
 
     bd_size_t write_read_buf_size = program_size;
-    if (contiguous_erase_size / program_size > 8 && contiguous_erase_size % (program_size * 8) == 0) {
-        write_read_buf_size = program_size * 8;
+
+    // Reading/writing in larger chunks reduces the number of operations,
+    // helping to avoid test timeouts. Try 256-byte chunks if contiguous_erase_size
+    // (which should be a power of 2) is greater than that. If it's less than
+    // that, the test finishes quickly anyway...
+    if ((program_size < 256) && (256 % program_size == 0)
+            && (contiguous_erase_size >= 256) && (contiguous_erase_size % 256 == 0)) {
+        utest_printf("using 256-byte write/read buffer\n");
+        write_read_buf_size = 256;
     }
 
     // Allocate write/read buffer