diff --git a/src/lattice.cpp b/src/lattice.cpp
index 5dc8b36..b81152d 100644
--- a/src/lattice.cpp
+++ b/src/lattice.cpp
@@ -1048,7 +1048,7 @@ void Lattice::displayReadReg(uint64_t dev)
 	uint8_t err;
 	printf("displayReadReg\n");
 	if (dev & 1<<0) printf("\tTRAN Mode\n");
-	printf("\tConfig Target Selection : %lx\n", (dev >> 1) & 0x07);
+	printf("\tConfig Target Selection : %llx\n", (dev >> 1) & 0x07);
 	if (dev & 1<<4) printf("\tJTAG Active\n");
 	if (dev & 1<<5) printf("\tPWD Protect\n");
 	if (dev & 1<<6) printf("\tOTP\n");
diff --git a/src/xilinx.cpp b/src/xilinx.cpp
index e8df0ed..834f869 100644
--- a/src/xilinx.cpp
+++ b/src/xilinx.cpp
@@ -385,7 +385,7 @@ Xilinx::Xilinx(Jtag *jtag, const std::string &filename,
 	if (read_dna) {
 		if (_fpga_family == ARTIX_FAMILY || _fpga_family == KINTEXUS_FAMILY) {
 			uint64_t dna = Xilinx::fuse_dna_read();
-			printf("{\"dna\": \"0x%016lx\"}\n", dna);
+			printf("{\"dna\": \"0x%016llx\"}\n", dna);
 		} else {
 			throw std::runtime_error("Error: read_xadc only supported for Artix 7");
 		}