diff --git a/contrib/minizip/zip.c b/contrib/minizip/zip.c
index 4e611e1..d1fccff 100644
--- a/contrib/minizip/zip.c
+++ b/contrib/minizip/zip.c
@@ -1083,6 +1083,20 @@ extern int ZEXPORT zipOpenNewFileInZip4_64 (zipFile file, const char* filename,
       return ZIP_PARAMERROR;
 #endif
 
+    // The filename and comment length must fit in 16 bits.
+    if ((filename != NULL) && (strlen(filename) > 0xffff)) {
+      return ZIP_PARAMERROR;
+    }
+    if ((comment != NULL) && (strlen(comment) > 0xffff)) {
+      return ZIP_PARAMERROR;
+    }
+    // The extra field length must fit in 16 bits. If the member also requires
+    // a Zip64 extra block, that will also need to fit within that 16-bit
+    // length, but that will be checked for later.
+    if ((size_extrafield_local > 0xffff) || (size_extrafield_global > 0xffff)) {
+      return ZIP_PARAMERROR;
+    }
+
     zi = (zip64_internal*)file;
 
     if (zi->in_opened_file_inzip == 1)