diff --git a/gguf-py/gguf/gguf.py b/gguf-py/gguf/gguf.py
index e4bfeaed2..326fe19ed 100644
--- a/gguf-py/gguf/gguf.py
+++ b/gguf-py/gguf/gguf.py
@@ -404,8 +404,8 @@ class GGUFWriter:
     def write_header_to_file(self):
         self.fout.write(struct.pack("<I", GGUF_MAGIC))
         self.fout.write(struct.pack("<I", GGUF_VERSION))
-        self.fout.write(struct.pack("<I", self.ti_data_count))
-        self.fout.write(struct.pack("<I", self.kv_data_count))
+        self.fout.write(struct.pack("<Q", self.ti_data_count))
+        self.fout.write(struct.pack("<Q", self.kv_data_count))
         self.flush()
 #        print("tensors " + str(self.ti_data_count) + " kv " + str(self.kv_data_count))
 
@@ -509,13 +509,13 @@ class GGUFWriter:
             self.kv_data += struct.pack("?", val)
         elif vtype == GGUFValueType.STRING:
             encoded_val = val.encode("utf8") if isinstance(val, str) else val
-            self.kv_data += struct.pack("<I", len(encoded_val))
+            self.kv_data += struct.pack("<Q", len(encoded_val))
             self.kv_data += encoded_val
         elif vtype == GGUFValueType.ARRAY:
             ltype = set([GGUFValueType.get_type(item) for item in val])
             assert len(ltype) == 1, "All items in a GGUF array should be of the same type"
             self.kv_data += struct.pack("<I", list(ltype)[0])
-            self.kv_data += struct.pack("<I", len(val))
+            self.kv_data += struct.pack("<Q", len(val))
             for item in val:
                 self.add_val(item, add_vtype=False)
         else:
@@ -529,10 +529,10 @@ class GGUFWriter:
         assert raw_dtype is not None or tensor_dtype in (np.float32, np.float16), "Only F32 and F16 tensors are supported for now"
 
         encoded_name = name.encode("utf8")
-        self.ti_data += struct.pack("<I", len(encoded_name))
+        self.ti_data += struct.pack("<Q", len(encoded_name))
         self.ti_data += encoded_name
         n_dims = len(tensor_shape)
-        self.ti_data += struct.pack("<I", n_dims)
+        self.ti_data += struct.pack("<Q", n_dims)
         for i in range(n_dims):
             self.ti_data += struct.pack("<Q", tensor_shape[n_dims - 1 - i])
         if raw_dtype is None: