diff --git a/compat/strtoumax.c b/compat/strtoumax.c
--- /dev/null
+++ b/compat/strtoumax.c
@@ -0,0 +1,10 @@
+#include "../git-compat-util.h"
+
+uintmax_t gitstrtoumax (const char *nptr, char **endptr, int base)
+{
+#if defined(NO_STRTOULL)
+ return strtoul(nptr, endptr, base);
+#else
+ return strtoull(nptr, endptr, base);
+#endif
+}