diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3ce3e70..ce75a8a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 This document contains the pymapvbvd release history in reverse chronological order.
 
+0.5.6 (Wednesday 11th October 2023)
+-----------------------------------
+- Fixed issue with large files on Windows. Thanks to FrankZijlstra for reporting.
+- Fixed subtle bug with precisely sized files interacting with memory chunking size. Thanks to FrankZijlstra for reporting. 
+
 0.5.5 (Tuesday 10th October 2023)
 ---------------------------------
 - Suppress warning `RuntimeWarning: invalid value encountered in cast`.
diff --git a/mapvbvd/mapVBVD.py b/mapvbvd/mapVBVD.py
index 185f03e..a82dd3b 100644
--- a/mapvbvd/mapVBVD.py
+++ b/mapvbvd/mapVBVD.py
@@ -140,7 +140,7 @@ def loop_mdh_read(fid, version, Nscans, scan, measOffset, measLength, print_prog
         n_acq = n_acq + 1
 
         # grow arrays in batches
-        if n_acq > szBlob:
+        if n_acq >= szBlob:
             grownArray = np.zeros((mdh_blob.shape[0], allocSize),
                                   dtype=np.uint8)  # pylint: disable=E1136  # pylint/issues/3139
             mdh_blob = np.concatenate((mdh_blob, grownArray), axis=1)
@@ -160,7 +160,7 @@ def loop_mdh_read(fid, version, Nscans, scan, measOffset, measLength, print_prog
 
         cPos = cPos + int(ulDMALength)
 
-    if isEOF or n_acq == len(filePos):
+    if isEOF:
         n_acq = n_acq - 1  # ignore the last attempt
     # import pdb; pdb.set_trace()
     filePos[n_acq] = cPos