diff --git a/src/fileio.cpp b/src/fileio.cpp
index 1458453958..e57c00a564 100644
--- a/src/fileio.cpp
+++ b/src/fileio.cpp
@@ -24,6 +24,7 @@
 #include <unistd.h>
 #include <pwd.h>
 #endif
+#include <charconv>
 #include <sys/stat.h>
 #include <sstream>
 #include <filesystem>
@@ -563,7 +564,16 @@ bool TarScanner::AddFile(const std::string &filename, size_t, [[maybe_unused]] c
 
 		/* The size of the file, for some strange reason, this is stored as a string in octals. */
 		std::string size = ExtractString(th.size);
-		size_t skip = size.empty() ? 0 : std::stoul(size, nullptr, 8);
+		size_t skip = 0;
+		if (!size.empty()) {
+			StrTrimInPlace(size);
+			auto [_, err] = std::from_chars(size.data(), size.data() + size.size(), skip, 8);
+			if (err != std::errc()) {
+				Debug(misc, 0, "The file '{}' has an invalid size for '{}'", filename, name);
+				fclose(f);
+				return false;
+			}
+		}
 
 		switch (th.typeflag) {
 			case '\0':