diff --git a/gp2040ce_bintools/pico.py b/gp2040ce_bintools/pico.py
index f81c9ca..f6a08c7 100644
--- a/gp2040ce_bintools/pico.py
+++ b/gp2040ce_bintools/pico.py
@@ -198,28 +198,38 @@ def write(out_end: usb.core.Endpoint, in_end: usb.core.Endpoint, location: int,
         location: memory address of where to start reading from
         content: the data to write
     """
-    # not sure why 256 alignment isn't working but it leads to corruption
-    # maybe claims that erase need to be on 4096 byte sectors?
-    if (location % 4096) != 0:
-        raise PicoAlignmentError("writes must start at 4096 byte boundaries, please pad or align as appropriate!")
+    chunk_size = 4096
+    write_location = location
+    write_size = 0
+
+    if (location % chunk_size) != 0:
+        raise PicoAlignmentError(f"writes must start at {chunk_size} byte boundaries, "
+                                 f"please pad or align as appropriate!")
 
     # set up the data
     command_size = 8
+    size = len(content)
 
     exclusive_access(out_end, in_end, is_exclusive=True)
-    exit_xip(out_end, in_end)
-    erase(out_end, in_end, location, len(content))
-    exit_xip(out_end, in_end)
-    pico_token = 1
-    logger.debug("writing %s bytes to %s", len(content), hex(location))
-    payload = struct.pack(PICOBOOT_CMD_STRUCT + PICOBOOT_CMD_READ_SUFFIX_STRUCT,
-                          PICO_MAGIC, pico_token, PICO_COMMANDS['WRITE'], command_size, len(content),
-                          location, len(content))
-    logger.debug("WRITE: %s", payload)
-    out_end.write(payload)
-    logger.debug("actually writing bytes now...")
-    logger.debug("payload: %s", content)
-    out_end.write(content)
-    res = in_end.read(256)
-    logger.debug("res: %s", res)
+    while write_size < size:
+        pico_token = 1
+        to_write = content[write_size:(write_size + chunk_size)]
+
+        exit_xip(out_end, in_end)
+        logger.debug("erasing %s bytes at %s", len(to_write), hex(write_location))
+        erase(out_end, in_end, write_location, len(to_write))
+
+        logger.debug("writing %s bytes to %s", len(to_write), hex(write_location))
+        payload = struct.pack(PICOBOOT_CMD_STRUCT + PICOBOOT_CMD_READ_SUFFIX_STRUCT,
+                              PICO_MAGIC, pico_token, PICO_COMMANDS['WRITE'], command_size, len(to_write),
+                              write_location, len(to_write))
+        logger.debug("WRITE: %s", payload)
+        out_end.write(payload)
+        logger.debug("actually writing bytes now...")
+        logger.debug("payload: %s", to_write)
+        out_end.write(bytes(to_write))
+        res = in_end.read(chunk_size)
+        logger.debug("res: %s", res)
+        write_size += chunk_size
+        write_location += chunk_size
     exclusive_access(out_end, in_end, is_exclusive=False)
diff --git a/tests/test_pico.py b/tests/test_pico.py
index ec502a3..39f65d7 100644
--- a/tests/test_pico.py
+++ b/tests/test_pico.py
@@ -178,13 +178,34 @@ def test_write():
         mock.call(struct.pack('<LLBBxxLL12x', 0x431fd10b, 1, 0x1, 1, 0, 1)),
         mock.call(struct.pack('<LLBBxxL16x', 0x431fd10b, 1, 0x6, 0, 0)),
         mock.call(struct.pack('<LLBBxxLLL8x', 0x431fd10b, 1, 0x3, 8, 0, 0x101FE000, 4)),
-        mock.call(struct.pack('<LLBBxxL16x', 0x431fd10b, 1, 0x6, 0, 0)),
         mock.call(struct.pack('<LLBBxxLLL8x', 0x431fd10b, 1, 0x5, 8, 4, 0x101FE000, 4)),
         mock.call(b'\x00\x01\x02\x03'),
         mock.call(struct.pack('<LLBBxxLL12x', 0x431fd10b, 1, 0x1, 1, 0, 0)),
     ]
     end_out.write.assert_has_calls(expected_writes)
-    assert end_in.read.call_count == 6
+    assert end_in.read.call_count == 5
+
+
+def test_write_chunked():
+    """Test that we can write to a board in BOOTSEL mode."""
+    end_out, end_in = mock.MagicMock(), mock.MagicMock()
+    payload = bytearray(b'\x00\x01\x02\x03' * 1024)
+    _ = pico.write(end_out, end_in, 0x10100000, payload * 2)
+
+    expected_writes = [
+        mock.call(struct.pack('<LLBBxxLL12x', 0x431fd10b, 1, 0x1, 1, 0, 1)),
+        mock.call(struct.pack('<LLBBxxL16x', 0x431fd10b, 1, 0x6, 0, 0)),
+        mock.call(struct.pack('<LLBBxxLLL8x', 0x431fd10b, 1, 0x3, 8, 0, 0x10100000, 4096)),
+        mock.call(struct.pack('<LLBBxxLLL8x', 0x431fd10b, 1, 0x5, 8, 4096, 0x10100000, 4096)),
+        mock.call(bytes(payload)),
+        mock.call(struct.pack('<LLBBxxL16x', 0x431fd10b, 1, 0x6, 0, 0)),
+        mock.call(struct.pack('<LLBBxxLLL8x', 0x431fd10b, 1, 0x3, 8, 0, 0x10100000 + 4096, 4096)),
+        mock.call(struct.pack('<LLBBxxLLL8x', 0x431fd10b, 1, 0x5, 8, 4096, 0x10100000 + 4096, 4096)),
+        mock.call(bytes(payload)),
+        mock.call(struct.pack('<LLBBxxLL12x', 0x431fd10b, 1, 0x1, 1, 0, 0)),
+    ]
+    end_out.write.assert_has_calls(expected_writes)
+    assert end_in.read.call_count == 8
 
 
 def test_misaligned_write():
@@ -216,10 +237,9 @@ def test_misaligned_write():
         mock.call(struct.pack('<LLBBxxLL12x', 0x431fd10b, 1, 0x1, 1, 0, 1)),
         mock.call(struct.pack('<LLBBxxL16x', 0x431fd10b, 1, 0x6, 0, 0)),
         mock.call(struct.pack('<LLBBxxLLL8x', 0x431fd10b, 1, 0x3, 8, 0, 0x101FF000, 4)),
-        mock.call(struct.pack('<LLBBxxL16x', 0x431fd10b, 1, 0x6, 0, 0)),
         mock.call(struct.pack('<LLBBxxLLL8x', 0x431fd10b, 1, 0x5, 8, 4, 0x101FF000, 4)),
         mock.call(b'\x00\x01\x02\x03'),
         mock.call(struct.pack('<LLBBxxLL12x', 0x431fd10b, 1, 0x1, 1, 0, 0)),
     ]
     end_out.write.assert_has_calls(expected_writes)
-    assert end_in.read.call_count == 6
+    assert end_in.read.call_count == 5