diff --git a/xpcom/ds/nsPageMgr.cpp b/xpcom/ds/nsPageMgr.cpp
index 422750a373bc..87f3dcdfde22 100644
--- a/xpcom/ds/nsPageMgr.cpp
+++ b/xpcom/ds/nsPageMgr.cpp
@@ -366,16 +366,16 @@ nsPageMgr::InitPages(nsPageCount minPages, nsPageCount maxPages)
 
     nsPage* addr = NULL;
     nsPageCount size = maxPages;
-    int zero_fd;
+    mZero_fd == NULL;
 
-    zero_fd = open("/dev/zero", O_RDWR);
+    mZero_fd = open("/dev/zero", O_RDWR);
 
     while (addr == NULL) {
         /* let the system place the heap */
         addr = (nsPage*)mmap(0, size << NS_PAGEMGR_PAGE_BITS,
                              PROT_READ | PROT_WRITE,
                              MAP_PRIVATE,
-                             zero_fd, 0);
+                             mZero_fd, 0);
         if (addr == (nsPage*)MAP_FAILED) {
             addr = NULL;
             size--;
@@ -433,6 +433,7 @@ nsPageMgr::FinalizePages()
 
 #else
     munmap((caddr_t)mMemoryBase, mPageCount << NS_PAGEMGR_PAGE_BITS);
+    close(mZero_fd);
 #endif
 }
 
diff --git a/xpcom/ds/nsPageMgr.h b/xpcom/ds/nsPageMgr.h
index 0fa019871981..5eb5986486d9 100644
--- a/xpcom/ds/nsPageMgr.h
+++ b/xpcom/ds/nsPageMgr.h
@@ -191,6 +191,11 @@ class nsPageMgr : public nsIPageManager, public nsIAllocator {
 #if defined(XP_BEOS)
 	area_id				mAid;
 #endif
+
+#if (! defined(VMS)) && (! defined(XP_BEOS)) && (! defined(XP_MAC)) && (! defined(XP_PC))
+    int mZero_fd;
+#endif
+
 };
 
 /******************************************************************************/