diff --git a/include/uv.h b/include/uv.h
index b89e637e..179398d6 100644
--- a/include/uv.h
+++ b/include/uv.h
@@ -1127,8 +1127,8 @@ int uv_ip6_name(struct sockaddr_in6* src, char* dst, size_t size);
 int uv_exepath(char* buffer, size_t* size);
 
 /* Gets memory info in bytes */
-double uv_get_free_memory(void);
-double uv_get_total_memory(void);
+uint64_t uv_get_free_memory(void);
+uint64_t uv_get_total_memory(void);
 
 /*
  * Returns the current high-resolution real time. This is expressed in
diff --git a/src/unix/cygwin.c b/src/unix/cygwin.c
index bafe83bf..2f0680a4 100644
--- a/src/unix/cygwin.c
+++ b/src/unix/cygwin.c
@@ -58,12 +58,12 @@ int uv_exepath(char* buffer, size_t* size) {
   return 0;
 }
 
-double uv_get_free_memory(void) {
-  return (double) sysconf(_SC_PAGESIZE) * sysconf(_SC_AVPHYS_PAGES);
+uint64_t uv_get_free_memory(void) {
+  return (uint64_t) sysconf(_SC_PAGESIZE) * sysconf(_SC_AVPHYS_PAGES);
 }
 
-double uv_get_total_memory(void) {
-  return (double) sysconf(_SC_PAGESIZE) * sysconf(_SC_PHYS_PAGES);
+uint64_t uv_get_total_memory(void) {
+  return (uint64_t) sysconf(_SC_PAGESIZE) * sysconf(_SC_PHYS_PAGES);
 }
 
 int uv_fs_event_init(uv_loop_t* loop,
diff --git a/src/unix/darwin.c b/src/unix/darwin.c
index a518cb26..675e0ad4 100644
--- a/src/unix/darwin.c
+++ b/src/unix/darwin.c
@@ -71,7 +71,7 @@ int uv_exepath(char* buffer, size_t* size) {
   return 0;
 }
 
-double uv_get_free_memory(void) {
+uint64_t uv_get_free_memory(void) {
   vm_statistics_data_t info;
   mach_msg_type_number_t count = sizeof(info) / sizeof(integer_t);
 
@@ -80,10 +80,10 @@ double uv_get_free_memory(void) {
     return -1;
   }
 
-  return (double) info.free_count * sysconf(_SC_PAGESIZE);
+  return (uint64_t) info.free_count * sysconf(_SC_PAGESIZE);
 }
 
-double uv_get_total_memory(void) {
+uint64_t uv_get_total_memory(void) {
   uint64_t info;
   int which[] = {CTL_HW, HW_MEMSIZE};
   size_t size = sizeof(info);
@@ -92,7 +92,7 @@ double uv_get_total_memory(void) {
     return -1;
   }
 
-  return (double) info;
+  return (uint64_t) info;
 }
 
 void uv_loadavg(double avg[3]) {
diff --git a/src/unix/freebsd.c b/src/unix/freebsd.c
index 5609ac4c..cd14d226 100644
--- a/src/unix/freebsd.c
+++ b/src/unix/freebsd.c
@@ -70,7 +70,7 @@ int uv_exepath(char* buffer, size_t* size) {
   return 0;
 }
 
-double uv_get_free_memory(void) {
+uint64_t uv_get_free_memory(void) {
   int freecount;
   size_t size = sizeof(freecount);
 
@@ -78,11 +78,11 @@ double uv_get_free_memory(void) {
                   &freecount, &size, NULL, 0) == -1){
     return -1;
   }
-  return (double) freecount * sysconf(_SC_PAGESIZE);
+  return (uint64_t) freecount * sysconf(_SC_PAGESIZE);
 
 }
 
-double uv_get_total_memory(void) {
+uint64_t uv_get_total_memory(void) {
   unsigned long info;
   int which[] = {CTL_HW, HW_PHYSMEM};
 
@@ -92,7 +92,7 @@ double uv_get_total_memory(void) {
     return -1;
   }
 
-  return (double) info;
+  return (uint64_t) info;
 }
 
 void uv_loadavg(double avg[3]) {
diff --git a/src/unix/linux.c b/src/unix/linux.c
index fb499a97..e7ca1840 100644
--- a/src/unix/linux.c
+++ b/src/unix/linux.c
@@ -75,12 +75,12 @@ int uv_exepath(char* buffer, size_t* size) {
   return 0;
 }
 
-double uv_get_free_memory(void) {
-  return (double) sysconf(_SC_PAGESIZE) * sysconf(_SC_AVPHYS_PAGES);
+uint64_t uv_get_free_memory(void) {
+  return (uint64_t) sysconf(_SC_PAGESIZE) * sysconf(_SC_AVPHYS_PAGES);
 }
 
-double uv_get_total_memory(void) {
-  return (double) sysconf(_SC_PAGESIZE) * sysconf(_SC_PHYS_PAGES);
+uint64_t uv_get_total_memory(void) {
+  return (uint64_t) sysconf(_SC_PAGESIZE) * sysconf(_SC_PHYS_PAGES);
 }
 
 static int new_inotify_fd(void) {
diff --git a/src/unix/netbsd.c b/src/unix/netbsd.c
index ff42e8ce..8b91f65c 100644
--- a/src/unix/netbsd.c
+++ b/src/unix/netbsd.c
@@ -82,7 +82,7 @@ int uv_exepath(char* buffer, size_t* size) {
   return 0;
 }
 
-double uv_get_free_memory(void) {
+uint64_t uv_get_free_memory(void) {
   struct uvmexp info;
   size_t size = sizeof(info);
   int which[] = {CTL_VM, VM_UVMEXP};
@@ -91,10 +91,10 @@ double uv_get_free_memory(void) {
     return -1;
   }
 
-  return (double) info.free * psysconf(_SC_PAGESIZE);
+  return (uint64_t) info.free * psysconf(_SC_PAGESIZE);
 }
 
-double uv_get_total_memory(void) {
+uint64_t uv_get_total_memory(void) {
 #if defined(HW_PHYSMEM64)
   uint64_t info;
   int which[] = {CTL_HW, HW_PHYSMEM64};
@@ -108,5 +108,5 @@ double uv_get_total_memory(void) {
     return -1;
   }
 
-  return (double) info;
+  return (uint64_t) info;
 }
diff --git a/src/unix/openbsd.c b/src/unix/openbsd.c
index 98af6d0f..55f8ceb0 100644
--- a/src/unix/openbsd.c
+++ b/src/unix/openbsd.c
@@ -98,7 +98,7 @@ out:
   return status;
 }
 
-double uv_get_free_memory(void) {
+uint64_t uv_get_free_memory(void) {
   struct uvmexp info;
   size_t size = sizeof(info);
   int which[] = {CTL_VM, VM_UVMEXP};
@@ -107,10 +107,10 @@ double uv_get_free_memory(void) {
     return -1;
   }
 
-  return (double) info.free * sysconf(_SC_PAGESIZE);
+  return (uint64_t) info.free * sysconf(_SC_PAGESIZE);
 }
 
-double uv_get_total_memory(void) {
+uint64_t uv_get_total_memory(void) {
   uint64_t info;
   int which[] = {CTL_HW, HW_PHYSMEM64};
   size_t size = sizeof(info);
@@ -119,5 +119,5 @@ double uv_get_total_memory(void) {
     return -1;
   }
 
-  return (double) info;
+  return (uint64_t) info;
 }
diff --git a/src/unix/sunos.c b/src/unix/sunos.c
index 9c717021..c0bfe32e 100644
--- a/src/unix/sunos.c
+++ b/src/unix/sunos.c
@@ -66,13 +66,13 @@ int uv_exepath(char* buffer, size_t* size) {
 }
 
 
-double uv_get_free_memory(void) {
-  return (double) sysconf(_SC_PAGESIZE) * sysconf(_SC_AVPHYS_PAGES);
+uint64_t uv_get_free_memory(void) {
+  return (uint64_t) sysconf(_SC_PAGESIZE) * sysconf(_SC_AVPHYS_PAGES);
 }
 
 
-double uv_get_total_memory(void) {
-  return (double) sysconf(_SC_PAGESIZE) * sysconf(_SC_PHYS_PAGES);
+uint64_t uv_get_total_memory(void) {
+  return (uint64_t) sysconf(_SC_PAGESIZE) * sysconf(_SC_PHYS_PAGES);
 }
 
 
diff --git a/src/win/util.c b/src/win/util.c
index cc6f93cf..3bc3e1db 100644
--- a/src/win/util.c
+++ b/src/win/util.c
@@ -103,7 +103,7 @@ void uv_loadavg(double avg[3]) {
 }
 
 
-double uv_get_free_memory(void) {
+uint64_t uv_get_free_memory(void) {
   MEMORYSTATUSEX memory_status;
   memory_status.dwLength = sizeof(memory_status);
 
@@ -112,11 +112,11 @@ double uv_get_free_memory(void) {
      return -1;
   }
 
-  return (double)memory_status.ullAvailPhys;
+  return (uint64_t)memory_status.ullAvailPhys;
 }
 
 
-double uv_get_total_memory(void) {
+uint64_t uv_get_total_memory(void) {
   MEMORYSTATUSEX memory_status;
   memory_status.dwLength = sizeof(memory_status);
 
@@ -125,7 +125,7 @@ double uv_get_total_memory(void) {
     return -1;
   }
 
-  return (double)memory_status.ullTotalPhys;
+  return (uint64_t)memory_status.ullTotalPhys;
 }
 
 
diff --git a/test/test-get-memory.c b/test/test-get-memory.c
index 502927d3..00281af6 100644
--- a/test/test-get-memory.c
+++ b/test/test-get-memory.c
@@ -23,10 +23,10 @@
 #include "task.h"
 
 TEST_IMPL(get_memory) {
-  double free_mem = uv_get_free_memory();
-  double total_mem = uv_get_total_memory();
+  uint64_t free_mem = uv_get_free_memory();
+  uint64_t total_mem = uv_get_total_memory();
 
-  printf("free_mem=%.0f, total_mem=%.0f\n", free_mem, total_mem);
+  printf("free_mem=%llu, total_mem=%llu\n", free_mem, total_mem);
 
   ASSERT(free_mem > 0);
   ASSERT(total_mem > 0);