diff --git a/ft8/libldpc.cpp b/ft8/libldpc.cpp
index 17d572df8..ad1cb71d8 100644
--- a/ft8/libldpc.cpp
+++ b/ft8/libldpc.cpp
@@ -363,7 +363,7 @@ void LDPC::ldpc_decode_log(float codeword[], int iters, int plain[], int *ok)
 // check the FT8 CRC-14
 //
 
-void LDPC::ft8_crc(int msg1[], int msglen, int out[14])
+void LDPC::ft8_crc(int msg1[], uint32_t msglen, int out[14])
 {
     // the old FT8 polynomial for 12-bit CRC, 0xc06.
     // int div[] = { 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0 };
@@ -375,7 +375,7 @@ void LDPC::ft8_crc(int msg1[], int msglen, int out[14])
     std::vector<int> msg(msglen + 14);
     std::memcpy(msg.data(), msg1, msglen * sizeof(int));
 
-    for (int i = 0; i < msglen; i++)
+    for (uint32_t i = 0; i < msglen; i++)
     {
         if (msg[i])
         {
diff --git a/ft8/libldpc.h b/ft8/libldpc.h
index 1d7208ea5..244120a03 100644
--- a/ft8/libldpc.h
+++ b/ft8/libldpc.h
@@ -22,13 +22,15 @@
 #ifndef libldpc_h
 #define libldpc_h
 
+#include <cstdint>
+
 namespace FT8 {
 
 class LDPC {
 public:
     static void ldpc_decode(const float llcodeword[], int iters, int plain[], int *ok);
     static void ldpc_decode_log(float codeword[], int iters, int plain[], int *ok);
-    static void ft8_crc(int msg1[], int msglen, int out[14]);
+    static void ft8_crc(int msg1[], uint32_t msglen, int out[14]);
     static void gauss_jordan(int rows, int cols, int m[174][2 * 91], int which[91], int *ok);
 
 private: