diff --git a/tangostationcontrol/tangostationcontrol/devices/sdp/sdp.py b/tangostationcontrol/tangostationcontrol/devices/sdp/sdp.py
index eb9d1c5d41d917a98f9cdd8687630eae0ff9067a..db7c1ffbcc8be04af296e14df3c0fe98e77b9da0 100644
--- a/tangostationcontrol/tangostationcontrol/devices/sdp/sdp.py
+++ b/tangostationcontrol/tangostationcontrol/devices/sdp/sdp.py
@@ -237,7 +237,7 @@ class SDP(opcua_device):
 
         # wait for the firmware to be loaded (ignoring masked out elements)
         mask = self.proxy.TR_fpga_mask_RW
-        self.wait_attribute("FPGA_boot_image_R", lambda attr: (attr == 1) | ~mask, 10)
+        self.wait_attribute("FPGA_boot_image_R", lambda attr: ((attr == 1) | ~mask).all(), 10)
 
     # --------
     # Commands