diff --git a/src/os.c b/src/os.c
index 3de708d1..740b8954 100644
--- a/src/os.c
+++ b/src/os.c
@@ -297,7 +297,7 @@ static void* mi_win_virtual_alloc(void* addr, size_t size, size_t try_alignment,
       if (large_only) return p;
       // fall back to non-large page allocation on error (`p == NULL`).
       if (p == NULL) {
-        mi_atomic_store_release(&large_page_try_ok,10);  // on error, don't try again for the next N allocations
+        mi_atomic_store_release(&large_page_try_ok,10UL);  // on error, don't try again for the next N allocations
       }
     }
   }
@@ -421,7 +421,7 @@ static void* mi_unix_mmap(void* addr, size_t size, size_t try_alignment, int pro
         #endif
         if (large_only) return p;
         if (p == NULL) {
-          mi_atomic_store_release(&large_page_try_ok, 10);  // on error, don't try again for the next N allocations
+          mi_atomic_store_release(&large_page_try_ok, 10UL);  // on error, don't try again for the next N allocations
         }
       }
     }
diff --git a/src/random.c b/src/random.c
index 4736a0ba..a604b49b 100644
--- a/src/random.c
+++ b/src/random.c
@@ -214,7 +214,7 @@ static bool os_random_buf(void* buf, size_t buf_len) {
     ssize_t ret = syscall(SYS_getrandom, buf, buf_len, GRND_NONBLOCK);
     if (ret >= 0) return (buf_len == (size_t)ret);
     if (ret != ENOSYS) return false;
-    mi_atomic_store_release(&no_getrandom,1); // don't call again, and fall back to /dev/urandom
+    mi_atomic_store_release(&no_getrandom, 1UL); // don't call again, and fall back to /dev/urandom
   }
 #endif
   int flags = O_RDONLY;