diff --git a/lib/card10/pb.c b/lib/card10/pb.c
index 8f97b8709628170b121c0744072a3fa7d38bc494..42525527a86aa117121638863c47b5f20b271a3f 100644
--- a/lib/card10/pb.c
+++ b/lib/card10/pb.c
@@ -110,7 +110,7 @@ void PB_IntClear(unsigned int pb)
 int PB_Get(unsigned int pb)
 {
 	static const uint8_t expander_pins[] = { 5, 0x0, 3, 6 };
-	MXC_ASSERT(pb < 4);
+	MXC_ASSERT(pb <= 4);
 	switch (pb) {
 	case 1:
 	case 3: