diff --git a/firmware/common/acars_packet.cpp b/firmware/common/acars_packet.cpp
index 2cf0366e..4a0e46bd 100644
--- a/firmware/common/acars_packet.cpp
+++ b/firmware/common/acars_packet.cpp
@@ -84,7 +84,7 @@ bool Packet::crc_ok() const {
 		acars_fcs.process_byte(field_crc.read(i, 8));
 	}
 
-	return (acars_fcs.checksum() == field_crc.read(data_length(), fcs_length));
+	return (acars_fcs.checksum() == (unsigned)field_crc.read(data_length(), fcs_length));
 }
 
 size_t Packet::data_and_fcs_length() const {
diff --git a/firmware/common/ais_packet.cpp b/firmware/common/ais_packet.cpp
index 61fabd89..c6e7561f 100644
--- a/firmware/common/ais_packet.cpp
+++ b/firmware/common/ais_packet.cpp
@@ -191,7 +191,7 @@ bool Packet::crc_ok() const {
 		ais_fcs.process_byte(field_crc.read(i, 8));
 	}
 
-	return (ais_fcs.checksum() == field_crc.read(data_length(), fcs_length));
+	return (ais_fcs.checksum() == (unsigned)field_crc.read(data_length(), fcs_length));
 }
 
 size_t Packet::data_and_fcs_length() const {