diff --git a/master/fsm_foe.c b/master/fsm_foe.c
index b722fd7c..bfa534e0 100644
--- a/master/fsm_foe.c
+++ b/master/fsm_foe.c
@@ -806,6 +806,13 @@ void ec_fsm_foe_state_data_read(
         return;
     }
 
+    if (rec_size < EC_FOE_HEADER_SIZE) {
+        EC_SLAVE_ERR(slave, "Received corrupted FoE size (%zu bytes)!\n",
+                rec_size);
+        ec_foe_set_rx_error(fsm, FOE_PROT_ERROR);
+        return;
+    }
+
     rec_size -= EC_FOE_HEADER_SIZE;
 
     if (fsm->rx_buffer_size >= fsm->rx_buffer_offset + rec_size) {