diff --git a/SPISlave_T4/SPISlave_T4.tpp b/SPISlave_T4/SPISlave_T4.tpp
index 7b270d8..f583f94 100644
--- a/SPISlave_T4/SPISlave_T4.tpp
+++ b/SPISlave_T4/SPISlave_T4.tpp
@@ -104,7 +104,7 @@ SPISlave_T4_FUNC uint32_t SPISlave_T4_OPT::popr() {
   return data;
 }
 
-extern uint32_t spiRx[256];
+extern uint8_t spiRx[256];
 extern volatile int spiRxIdx;
 
 SPISlave_T4_FUNC void __attribute__((section(".fustrun"))) SPISlave_T4_OPT::SLAVE_ISR() {