diff --git a/src/os/darwin/darwin_sigar.c b/src/os/darwin/darwin_sigar.c
index 59314dba..6dda00de 100644
--- a/src/os/darwin/darwin_sigar.c
+++ b/src/os/darwin/darwin_sigar.c
@@ -489,6 +489,13 @@ int sigar_mem_get(sigar_t *sigar, sigar_mem_t *mem)
         return status;
     }
     mem->free = vmstat.free;
+    kern = vmstat.inactive;
+#  if defined(__OpenBSD__)
+    kern += vmstat.vnodepages + vmstat.vtextpages;
+# elif defined(__NetBSD__)
+    kern += vmstat.filepages + vmstat.execpages;
+#  endif
+    kern *= sigar->pagesize;
 #endif
 
     mem->used = mem->total - mem->free;