diff --git a/File.cpp b/File.cpp
index 9ef8196..4d7cf1e 100644
--- a/File.cpp
+++ b/File.cpp
@@ -97,7 +97,10 @@ int File::read(void *buf, uint16_t nbyte) {
 
 int File::available() {
   if (! _file) return 0;
-  return size() - position();
+
+  uint32_t n = size() - position();
+
+  return n > 0X7FFF ? 0X7FFF : n;
 }
 
 void File::flush() {