diff --git a/src/util/platform.cpp b/src/util/platform.cpp
index 2c3c5f0..c471aca 100644
--- a/src/util/platform.cpp
+++ b/src/util/platform.cpp
@@ -187,11 +187,15 @@ bool Platform::openFolder(const std::string& path, bool createIfMissing)
 
 uint64_t Platform::getFileSize(const std::string& path)
 {
-    struct stat st;
-    if (stat(path.c_str(), &st) == 0) {
-        return static_cast<uint64_t>(st.st_size);
-    }
-    return 0;
+    // Use std::filesystem (64-bit uintmax_t) rather than stat(): on mingw/Windows struct stat's
+    // st_size is a 32-bit signed _off_t, so a wallet.dat over 2 GiB overflows negative and casts to a
+    // garbage ~2^64 value (the "17179869182 GB" bug). The error_code overload returns on failure
+    // (missing / unreadable / Windows sharing violation while the daemon holds the file) instead of
+    // throwing, and we report 0 so callers fall back to "unknown".
+    std::error_code ec;
+    const auto sz = std::filesystem::file_size(path, ec);
+    if (ec) return 0;
+    return static_cast<uint64_t>(sz);
 }
 
 std::string Platform::formatFileSize(uint64_t bytes)