diff --git a/src/mkfat.c b/src/mkfat.c
index 3605620..0fe12aa 100644
--- a/src/mkfat.c
+++ b/src/mkfat.c
@@ -13,7 +13,7 @@ int fat12_mkfs(int fd, uint32_t bytes) {
     uint8_t mbr[512];
     const uint32_t sector_size  = 512;
     uint32_t cluster_size = 4096 / sector_size; // 4 kiB cluster sizes match flash erase block size
-    if (bytes > 16000) {
+    if (bytes > 16000000) {
         // We run out of clusters just below 16 megabytes.  Use bigger cluseters.
         cluster_size = 8192 / sector_size;
     }