diff --git a/hid.pyx b/hid.pyx
index cb05e72..ea93696 100644
--- a/hid.pyx
+++ b/hid.pyx
@@ -231,7 +231,7 @@ cdef class device:
             else:
                 with nogil:
                     n = hid_read(c_hid, cbuff, c_max_length)
-            if n is -1:
+            if n == -1:
                 raise IOError('read error')
             res = list(cbuff[:n])
         finally: