diff --git a/hw/application_fpga/fw/testfw/main.c b/hw/application_fpga/fw/testfw/main.c
index a10c16d..81e6fbb 100644
--- a/hw/application_fpga/fw/testfw/main.c
+++ b/hw/application_fpga/fw/testfw/main.c
@@ -29,6 +29,10 @@ volatile uint32_t *fw_blake2s_addr = (volatile uint32_t *)TK1_MMIO_TK1_BLAKE2S;
 volatile int (*fw_blake2s)(void *, unsigned long, const void *, unsigned long, const void *, unsigned long, blake2s_ctx *);
 // clang-format on
 
+#define UDS_WORDS 8
+#define UDI_WORDS 2
+#define CDI_WORDS 8
+
 void puts(char *reason)
 {
 	for (char *c = reason; *c != '\0'; c++) {
@@ -111,42 +115,41 @@ int main()
 	putsn((char *)&name, 4);
 	puts("\r\n");
 
+	uint32_t zeros[8];
+	memset(zeros, 0, 8 * 4);
+
 	int anyfailed = 0;
 
-	uint32_t uds_local[8];
-	uint32_t uds_zeros[8];
-	memset(uds_zeros, 0, 8 * 4);
+	uint32_t uds_local[UDS_WORDS];
 	// Should get non-empty UDS
-	wordcpy(uds_local, (void *)uds, 8);
-	if (memeq(uds_local, uds_zeros, 8 * 4)) {
+	wordcpy(uds_local, (void *)uds, UDS_WORDS);
+	if (memeq(uds_local, zeros, UDS_WORDS * 4)) {
 		puts("FAIL: UDS empty\r\n");
 		anyfailed = 1;
 	}
 	// Should NOT be able to read from UDS again
-	wordcpy(uds_local, (void *)uds, 8);
-	if (!memeq(uds_local, uds_zeros, 8 * 4)) {
+	wordcpy(uds_local, (void *)uds, UDS_WORDS);
+	if (!memeq(uds_local, zeros, UDS_WORDS * 4)) {
 		puts("FAIL: Read UDS a second time\r\n");
 		anyfailed = 1;
 	}
 
-	uint32_t udi_local[2];
-	uint32_t udi_zeros[2];
-	memset(udi_zeros, 0, 2 * 4);
+	uint32_t udi_local[UDI_WORDS];
 	// Should get non-empty UDI
-	wordcpy(udi_local, (void *)udi, 2);
-	if (memeq(udi_local, udi_zeros, 2 * 4)) {
+	wordcpy(udi_local, (void *)udi, UDI_WORDS);
+	if (memeq(udi_local, zeros, UDI_WORDS * 4)) {
 		puts("FAIL: UDI empty\r\n");
 		anyfailed = 1;
 	}
 
 	// Should be able to write to CDI in fw (non-app) mode.
-	uint32_t cdi_writetest[8] = {0xdeafbeef, 0xdeafbeef, 0xdeafbeef,
-				     0xdeafbeef, 0xdeafbeef, 0xdeafbeef,
-				     0xdeafbeef, 0xdeafbeef};
-	uint32_t cdi_readback[8];
-	wordcpy((void *)cdi, cdi_writetest, 8);
-	wordcpy(cdi_readback, (void *)cdi, 8);
-	if (!memeq(cdi_writetest, cdi_readback, 8 * 4)) {
+	uint32_t cdi_writetest[CDI_WORDS] = {0xdeafbeef, 0xdeafbeef, 0xdeafbeef,
+					     0xdeafbeef, 0xdeafbeef, 0xdeafbeef,
+					     0xdeafbeef, 0xdeafbeef};
+	uint32_t cdi_readback[CDI_WORDS];
+	wordcpy((void *)cdi, cdi_writetest, CDI_WORDS);
+	wordcpy(cdi_readback, (void *)cdi, CDI_WORDS);
+	if (!memeq(cdi_writetest, cdi_readback, CDI_WORDS * 4)) {
 		puts("FAIL: Can't write CDI in fw mode\r\n");
 		anyfailed = 1;
 	}
@@ -178,21 +181,20 @@ int main()
 	}
 
 	// Should NOT be able to read from UDS in app-mode.
-	wordcpy(uds_local, (void *)uds, 8);
-	if (!memeq(uds_local, uds_zeros, 8 * 4)) {
+	wordcpy(uds_local, (void *)uds, UDS_WORDS);
+	if (!memeq(uds_local, zeros, UDS_WORDS * 4)) {
 		puts("FAIL: Read from UDS in app-mode\r\n");
 		anyfailed = 1;
 	}
 
-	uint32_t cdi_local[8];
-	uint32_t cdi_local2[8];
-	uint32_t cdi_zeros[8];
-	memset(cdi_zeros, 0, 8 * 4);
-	wordcpy(cdi_local, (void *)cdi, 8);
+	uint32_t cdi_local[CDI_WORDS];
+	uint32_t cdi_local2[CDI_WORDS];
+	wordcpy(cdi_local, (void *)cdi, CDI_WORDS);
+
 	// Write to CDI should NOT have any effect in app mode.
-	wordcpy((void *)cdi, cdi_zeros, 8);
-	wordcpy(cdi_local2, (void *)cdi, 8);
-	if (!memeq(cdi_local, cdi_local2, 8 * 4)) {
+	wordcpy((void *)cdi, zeros, CDI_WORDS);
+	wordcpy(cdi_local2, (void *)cdi, CDI_WORDS);
+	if (!memeq(cdi_local, cdi_local2, CDI_WORDS * 4)) {
 		puts("FAIL: Write to CDI in app-mode\r\n");
 		anyfailed = 1;
 	}