diff --git a/exec.c b/exec.c
index 7f62e71..53bad8c 100644
--- a/exec.c
+++ b/exec.c
@@ -2143,8 +2143,8 @@
 {
     ram_addr_t addr;
     if ((phys_ram_alloc_offset + size) > phys_ram_size) {
-        fprintf(stderr, "Not enough memory (requested_size = %lu, max memory = %ld)\n",
-                size, phys_ram_size);
+        fprintf(stderr, "Not enough memory (requested_size = %" PRIu64 ", max memory = %" PRIu64 "\n",
+                (uint64_t)size, (uint64_t)phys_ram_size);
         abort();
     }
     addr = phys_ram_alloc_offset;