Index: lib/interception/interception.h
===================================================================
--- lib/interception/interception.h
+++ lib/interception/interception.h
@@ -29,6 +29,7 @@
 typedef __sanitizer::sptr    SSIZE_T;
 typedef __sanitizer::sptr    PTRDIFF_T;
 typedef __sanitizer::s64     INTMAX_T;
+typedef __sanitizer::u64     UINTMAX_T;
 typedef __sanitizer::OFF_T   OFF_T;
 typedef __sanitizer::OFF64_T OFF64_T;
 
Index: lib/sanitizer_common/sanitizer_common_interceptors.inc
===================================================================
--- lib/sanitizer_common/sanitizer_common_interceptors.inc
+++ lib/sanitizer_common/sanitizer_common_interceptors.inc
@@ -3345,14 +3345,14 @@
   return res;
 }
 
-INTERCEPTOR(INTMAX_T, strtoumax, const char *nptr, char **endptr, int base) {
+INTERCEPTOR(UINTMAX_T, strtoumax, const char *nptr, char **endptr, int base) {
   void *ctx;
   COMMON_INTERCEPTOR_ENTER(ctx, strtoumax, nptr, endptr, base);
   // FIXME: under ASan the call below may write to freed memory and corrupt
   // its metadata. See
   // https://github.com/google/sanitizers/issues/321.
   char *real_endptr;
-  INTMAX_T res = REAL(strtoumax)(nptr, &real_endptr, base);
+  UINTMAX_T res = REAL(strtoumax)(nptr, &real_endptr, base);
   StrtolFixAndCheck(ctx, nptr, endptr, real_endptr, base);
   return res;
 }