diff --git a/python/__init__.py b/python/__init__.py
index a1eb30f7..984b93f2 100644
--- a/python/__init__.py
+++ b/python/__init__.py
@@ -540,7 +540,7 @@ class Panda:
   # Returns tuple with health packet version and CAN packet/USB packet version
   def get_packets_versions(self):
     dat = self._handle.controlRead(Panda.REQUEST_IN, 0xdd, 0, 0, 3)
-    if dat:
+    if dat and len(dat) == 3:
       a = struct.unpack("BBB", dat)
       return (a[0], a[1], a[2])
     else: