diff --git a/docs/installation.rst b/docs/installation.rst
index efde6e931df..0b04b134e9b 100644
--- a/docs/installation.rst
+++ b/docs/installation.rst
@@ -162,7 +162,7 @@ Many of Pillow's features require external libraries:
 
 * **libtiff** provides compressed TIFF functionality
 
-  * Pillow has been tested with libtiff versions **3.x** and **4.0-4.3**
+  * Pillow has been tested with libtiff versions **3.x** and **4.0-4.4**
 
 * **libfreetype** provides type related services
 
diff --git a/src/libImaging/TiffDecode.c b/src/libImaging/TiffDecode.c
index f818f19d502..3bb444c804c 100644
--- a/src/libImaging/TiffDecode.c
+++ b/src/libImaging/TiffDecode.c
@@ -815,11 +815,11 @@ ImagingLibTiffMergeFieldInfo(
 
     // custom fields added with ImagingLibTiffMergeFieldInfo are only used for
     // decoding, ignore readcount;
-    int readcount = 1;
+    int readcount = is_var_length ? TIFF_VARIABLE : 1;
     // we support writing a single value, or a variable number of values
-    int writecount = 1;
+    int writecount = is_var_length ? TIFF_VARIABLE : 1;
     // whether the first value should encode the number of values.
-    int passcount = 0;
+    int passcount = (is_var_length && field_type != TIFF_ASCII) ? 1 : 0;
 
     TIFFFieldInfo info[] = {
         {key,
@@ -831,14 +831,6 @@ ImagingLibTiffMergeFieldInfo(
          passcount,
          "CustomField"}};
 
-    if (is_var_length) {
-        info[0].field_writecount = -1;
-    }
-
-    if (is_var_length && field_type != TIFF_ASCII) {
-        info[0].field_passcount = 1;
-    }
-
     n = sizeof(info) / sizeof(info[0]);
 
     // Test for libtiff 4.0 or later, excluding libtiff 3.9.6 and 3.9.7
diff --git a/winbuild/build_prepare.py b/winbuild/build_prepare.py
index 3d9391321a6..a963205c156 100644
--- a/winbuild/build_prepare.py
+++ b/winbuild/build_prepare.py
@@ -143,9 +143,9 @@ def cmd_msbuild(
         "libs": [r"*.lib"],
     },
     "libtiff": {
-        "url": "https://download.osgeo.org/libtiff/tiff-4.3.0.tar.gz",
-        "filename": "tiff-4.3.0.tar.gz",
-        "dir": "tiff-4.3.0",
+        "url": "https://download.osgeo.org/libtiff/tiff-4.4.0.tar.gz",
+        "filename": "tiff-4.4.0.tar.gz",
+        "dir": "tiff-4.4.0",
         "build": [
             cmd_cmake("-DBUILD_SHARED_LIBS:BOOL=OFF"),
             cmd_nmake(target="clean"),