diff --git a/configure.in b/configure.in
index baa77f371f..1d3f328ee8 100644
--- a/configure.in
+++ b/configure.in
@@ -1461,6 +1461,24 @@ AC_CHECK_TYPES([struct timeval], [], [], [@%:@ifdef HAVE_TIME_H
 @%:@include <sys/time.h>
 @%:@endif])
 
+if test "${ac_cv_type_struct_timeval}" = yes; then
+    RUBY_CHECK_SIZEOF([struct timeval.tv_sec], [time_t long "long long"], [],
+		      [@%:@ifdef HAVE_TIME_H
+@%:@include <time.h>
+@%:@endif
+@%:@ifdef HAVE_SYS_TIME_H
+@%:@include <sys/time.h>
+@%:@endif])
+    AS_CASE(${ac_cv_sizeof_struct_timeval_tv_sec},
+	    [SIZEOF_INT], [t=int],
+	    [SIZEOF_LONG], [t=long],
+	    [SIZEOF_LONG_LONG], [t=LONG_LONG],
+	    [t=])
+    if test "${t}" != ""; then
+	AC_DEFINE_UNQUOTED(TYPEOF_TIMEVAL_TV_SEC, [$t])
+    fi
+fi
+
 AC_CHECK_TYPES([struct timespec], [], [], [@%:@ifdef HAVE_TIME_H
 @%:@include <time.h>
 @%:@endif
diff --git a/thread.c b/thread.c
index 09c3b1d124..95b045fc54 100644
--- a/thread.c
+++ b/thread.c
@@ -915,18 +915,29 @@ thread_value(VALUE self)
 static struct timeval
 double2timeval(double d)
 {
+    /* assume timeval.tv_sec has same signedness as time_t */
+#if SIGNEDNESS_OF_TIME_T < 0	/* signed */
+    const unsigned_time_t TIMEVAL_SEC_MAX_P1 = (((unsigned_time_t)1) << (sizeof(TYPEOF_TIMEVAL_TV_SEC) * CHAR_BIT - 1));
+    const TYPEOF_TIMEVAL_TV_SEC TIMEVAL_SEC_MAX = (TYPEOF_TIMEVAL_TV_SEC)(TIMEVAL_SEC_MAX_P1 - 1);
+    const TYPEOF_TIMEVAL_TV_SEC TIMEVAL_SEC_MIN = (TYPEOF_TIMEVAL_TV_SEC)TIMEVAL_SEC_MAX_P1;
+#elif SIGNEDNESS_OF_TIME_T > 0	/* unsigned */
+    const TYPEOF_TIMEVAL_TV_SEC TIMEVAL_SEC_MAX = (TYPEOF_TIMEVAL_TV_SEC)(~(unsigned_time_t)0);
+    const TYPEOF_TIMEVAL_TV_SEC TIMEVAL_SEC_MIN = (TYPEOF_TIMEVAL_TV_SEC)0;
+#endif
+    const double TIMEVAL_SEC_MAX_PLUS_ONE = (2*(double)(TIMEVAL_SEC_MAX/2+1));
+
     struct timeval time;
 
-    if (TIMET_MAX_PLUS_ONE <= d) {
-        time.tv_sec = TIMET_MAX;
+    if (TIMEVAL_SEC_MAX_PLUS_ONE <= d) {
+        time.tv_sec = TIMEVAL_SEC_MAX;
         time.tv_usec = 999999;
     }
-    else if (d <= TIMET_MIN) {
-        time.tv_sec = TIMET_MIN;
+    else if (d <= TIMEVAL_SEC_MIN) {
+        time.tv_sec = TIMEVAL_SEC_MIN;
         time.tv_usec = 0;
     }
     else {
-        time.tv_sec = (time_t)d;
+        time.tv_sec = (TYPEOF_TIMEVAL_TV_SEC)d;
         time.tv_usec = (int)((d - (time_t)d) * 1e6);
         if (time.tv_usec < 0) {
             time.tv_usec += (int)1e6;