diff --git a/tapeget.lua b/tapeget.lua
index 2f1039c..1ba739b 100644
--- a/tapeget.lua
+++ b/tapeget.lua
@@ -49,7 +49,7 @@ if not req then
 end
 
 local headers = req.getResponseHeaders()
-local length = headers["content-length"] or 1
+local length = tonumber(headers["content-length"]) or 1
 
 if length > tape.getSize() then
     printError("Tape is smaller than the file you're trying to write")