diff --git a/src/main.c b/src/main.c
index 943775a..2098b2e 100644
--- a/src/main.c
+++ b/src/main.c
@@ -120,6 +120,8 @@ void read_can(Tel *t, int soc) {
 
         if (nbytes < 0) return; // -1 EAGAIN means empty
 
+        if (nbytes != sizeof(struct can_frame)) return;
+
         if (nbytes > 0) {
 
                 switch (frame.can_id) {