diff --git a/src/main.c b/src/main.c
index 5131292..2381f75 100644
--- a/src/main.c
+++ b/src/main.c
@@ -154,7 +154,7 @@ init_SDL(const char* path)
     return 1;
 }
 
-long
+uint64_t
 get_file_size(FILE* f)
 {
     if (fseek(f, 0, SEEK_END)) {
@@ -162,7 +162,7 @@ get_file_size(FILE* f)
         return 0;
     }
 
-    const long size = ftell(f);
+    const int64_t size = ftell(f);
     if (size == -1) {
         fputs("ERROR: Failed to get file size\n", stderr);
         return 0;
@@ -182,7 +182,7 @@ load_rom(const char* path)
         return 0;
     }
 
-    const long size = get_file_size(f);
+    const uint64_t size = get_file_size(f);
     if (!size) {
         if (fclose(f))
             fputs("ERROR: Failed to close rom file\n", stderr);
@@ -214,7 +214,7 @@ load_rom(const char* path)
 
     fputs("Loaded ROM:\n", stderr);
     uint_fast8_t c = 0;
-    for (long t = 0; t < size; t += 2) {
+    for (register uint64_t t = 0; t < size; t += 2) {
         fprintf(
           stderr, "%04X ", (memory[t + 0x200] << 8) + memory[t + 0x200 + 1]);
         if (++c == 8) {