diff --git a/ChangeLog b/ChangeLog
index 2fe1d05..7147925 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,6 @@
+2024-02-29  gdraheim@github
+    * disabled local file header offset64
+
 2024-02-28  gdraheim@github
     * fixed last cmake bug - parallel builds can lead to race condition
     * abolished centos8 testbuilds and prepared ubuntu24
diff --git a/zzip/fetch.h b/zzip/fetch.h
index 036902d..70d74a3 100644
--- a/zzip/fetch.h
+++ b/zzip/fetch.h
@@ -286,6 +286,7 @@ __zzip_set64(zzip_byte_t* s, uint64_t v);
 #define zzip_disk_trailer_to_endoffile(__p)                                                        \
     ((void*) (zzip_disk_trailer_to_comment(__p) + zzip_disk_trailer_comment(__p)))
 
+#define zzip_use_file_header_zip64_offset 0
 #define zzip_extra_zip64_csize(__p)     ((zzip_size_t) zzip_extra_zip64_get_csize(__p))
 #define zzip_extra_zip64_usize(__p)     ((zzip_size_t) zzip_extra_zip64_get_usize(__p))
 #define zzip_extra_zip64_offset(__p)    ((zzip_off_t) zzip_extra_zip64_get_offset(__p))
diff --git a/zzip/mmapped.c b/zzip/mmapped.c
index 13979ea..ab7d679 100644
--- a/zzip/mmapped.c
+++ b/zzip/mmapped.c
@@ -273,7 +273,7 @@ zzip_disk_entry_to_file_header(ZZIP_DISK* disk, struct zzip_disk_entry* entry)
 {
     zzip_byte_t* const ptr = disk->buffer + zzip_disk_entry_fileoffset(entry);
     zzip_byte_t* const end = ptr + sizeof(struct zzip_file_header);
-    if (disk->buffer > ptr || end >= disk->endbuf || end <= NULL) {
+    if (disk->buffer > ptr || end >= disk->endbuf || (void*)end <= NULL) {
         debug2("file header: offset out of bounds (0x%llx)", (long long unsigned) (disk->buffer));
         errno = EBADMSG;
         return 0;
@@ -626,7 +626,7 @@ zzip_disk_entry_fopen(ZZIP_DISK* disk, ZZIP_DISK_ENTRY* entry)
 
     ___ /* a ZIP64 extended block may follow. */
         size_t csize  = zzip_file_header_csize(header);
-    off_t      offset = zzip_file_header_to_data(header);
+    zzip_byte_t*  start = zzip_file_header_to_data(header);
     if (csize == 0xFFFFu) {
         struct zzip_extra_zip64* zip64 =
             (struct zzip_extra_zip64*) zzip_file_header_to_extras(header);
@@ -634,11 +634,29 @@ zzip_disk_entry_fopen(ZZIP_DISK* disk, ZZIP_DISK_ENTRY* entry)
             csize = zzip_extra_zip64_csize(zip64);
         }
     }
-    if (offset == 0xFFFFu) {
+
+    if (((unsigned long)start) & 0xFFFFu == 0xFFFFu) {
+        /* actually the ZIP64 rootseek in the central directory should have updated the 
+           header start with the data portion to follow right behind it. The usage of
+           this field in a local file header is wrong on a number of levels. Specifically
+           that the zip64 extended field value points to yet another header but it is
+           actually used to point to the actual data portion instead. */
         struct zzip_extra_zip64* zip64 =
             (struct zzip_extra_zip64*) zzip_file_header_to_extras(header);
         if (ZZIP_EXTRA_ZIP64_CHECK(zip64)) {
-            offset = zzip_extra_zip64_offset(zip64);
+            zzip_off64_t offset = zzip_extra_zip64_offset(zip64); /* offset of local header record */
+            if (offset && zzip_use_file_header_zip64_offset) {
+               start = disk->buffer + offset; /* but points directly to the data portion */
+               if (disk->buffer > start || start+csize >= disk->endbuf) {
+                    debug2("file start: offset out of bounds (0x%llx)", (long long unsigned) (offset));
+                    errno = EBADMSG;
+                    return 0;
+                }
+            } else {
+                debug1("file start: no zip64 local offset");
+                errno = EBADMSG;
+                return 0;
+            }
         }
     }
 
@@ -647,7 +665,7 @@ zzip_disk_entry_fopen(ZZIP_DISK* disk, ZZIP_DISK_ENTRY* entry)
     file->zlib.zalloc   = Z_NULL;
     file->zlib.zfree    = Z_NULL;
     file->zlib.avail_in = csize;
-    file->zlib.next_in  = offset;
+    file->zlib.next_in  = start;
     ____;
 
     DBG2("compressed size %i", (int) file->zlib.avail_in);