diff --git a/src/unix/cygwin.c b/src/unix/cygwin.c
index a3d17365..8849656f 100644
--- a/src/unix/cygwin.c
+++ b/src/unix/cygwin.c
@@ -34,7 +34,7 @@
 uint64_t uv_hrtime() {
   struct timespec ts;
   clock_gettime(CLOCK_MONOTONIC, &ts);
-  return (ts.tv_sec * NANOSEC + ts.tv_nsec);
+  return (((uint64_t) ts.tv_sec) * NANOSEC + ts.tv_nsec);
 }
 
 void uv_loadavg(double avg[3]) {
diff --git a/src/unix/freebsd.c b/src/unix/freebsd.c
index a519f86d..5d0c6f4c 100644
--- a/src/unix/freebsd.c
+++ b/src/unix/freebsd.c
@@ -38,7 +38,7 @@
 uint64_t uv_hrtime(void) {
   struct timespec ts;
   clock_gettime(CLOCK_MONOTONIC, &ts);
-  return (ts.tv_sec * NANOSEC + ts.tv_nsec);
+  return (((uint64_t) ts.tv_sec) * NANOSEC + ts.tv_nsec);
 }
 
 
diff --git a/src/unix/linux.c b/src/unix/linux.c
index a01d14b7..28346552 100644
--- a/src/unix/linux.c
+++ b/src/unix/linux.c
@@ -134,7 +134,7 @@ static char* basename_r(const char* path) {
 uint64_t uv_hrtime() {
   struct timespec ts;
   clock_gettime(CLOCK_MONOTONIC, &ts);
-  return (ts.tv_sec * NANOSEC + ts.tv_nsec);
+  return (((uint64_t) ts.tv_sec) * NANOSEC + ts.tv_nsec);
 }
 
 void uv_loadavg(double avg[3]) {
diff --git a/src/unix/netbsd.c b/src/unix/netbsd.c
index cf83c344..e4bea7ff 100644
--- a/src/unix/netbsd.c
+++ b/src/unix/netbsd.c
@@ -38,7 +38,7 @@
 uint64_t uv_hrtime(void) {
   struct timespec ts;
   clock_gettime(CLOCK_MONOTONIC, &ts);
-  return (ts.tv_sec * NANOSEC + ts.tv_nsec);
+  return (((uint64_t) ts.tv_sec) * NANOSEC + ts.tv_nsec);
 }
 
 void uv_loadavg(double avg[3]) {
diff --git a/src/unix/openbsd.c b/src/unix/openbsd.c
index 55f8ceb0..96e78fbd 100644
--- a/src/unix/openbsd.c
+++ b/src/unix/openbsd.c
@@ -36,7 +36,7 @@
 uint64_t uv_hrtime(void) {
   struct timespec ts;
   clock_gettime(CLOCK_MONOTONIC, &ts);
-  return (ts.tv_sec * NANOSEC + ts.tv_nsec);
+  return (((uint64_t) ts.tv_sec) * NANOSEC + ts.tv_nsec);
 }
 
 void uv_loadavg(double avg[3]) {