diff --git a/src/PIL/TiffImagePlugin.py b/src/PIL/TiffImagePlugin.py
index 6bf39b75a5f..c95b65b8ea2 100644
--- a/src/PIL/TiffImagePlugin.py
+++ b/src/PIL/TiffImagePlugin.py
@@ -1915,7 +1915,9 @@ def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
                 if not getattr(Image.core, "libtiff_support_custom_tags", False):
                     continue
 
-                if tag in ifd.tagtype:
+                if tag in TiffTags.TAGS_V2_GROUPS:
+                    types[tag] = TiffTags.LONG8
+                elif tag in ifd.tagtype:
                     types[tag] = ifd.tagtype[tag]
                 elif not (isinstance(value, (int, float, str, bytes))):
                     continue
diff --git a/src/encode.c b/src/encode.c
index 1a4cd489da2..d369a1b4598 100644
--- a/src/encode.c
+++ b/src/encode.c
@@ -736,7 +736,7 @@ PyImaging_LibTiffEncoderNew(PyObject *self, PyObject *args) {
             }
             if (tag_type) {
                 int type_int = PyLong_AsLong(tag_type);
-                if (type_int >= TIFF_BYTE && type_int <= TIFF_DOUBLE) {
+                if (type_int >= TIFF_BYTE && type_int <= TIFF_LONG8) {
                     type = (TIFFDataType)type_int;
                 }
             }
@@ -929,7 +929,7 @@ PyImaging_LibTiffEncoderNew(PyObject *self, PyObject *args) {
                 );
             } else if (type == TIFF_LONG) {
                 status = ImagingLibTiffSetField(
-                    &encoder->state, (ttag_t)key_int, PyLong_AsLongLong(value)
+                    &encoder->state, (ttag_t)key_int, (UINT32)PyLong_AsLong(value)
                 );
             } else if (type == TIFF_SSHORT) {
                 status = ImagingLibTiffSetField(
@@ -959,6 +959,10 @@ PyImaging_LibTiffEncoderNew(PyObject *self, PyObject *args) {
                 status = ImagingLibTiffSetField(
                     &encoder->state, (ttag_t)key_int, (FLOAT64)PyFloat_AsDouble(value)
                 );
+            } else if (type == TIFF_LONG8) {
+                status = ImagingLibTiffSetField(
+                    &encoder->state, (ttag_t)key_int, (uint64_t)PyLong_AsLongLong(value)
+                );
             } else {
                 TRACE(
                     ("Unhandled type for key %d : %s \n",