diff --git a/lib/isc/unix/meminfo.c b/lib/isc/unix/meminfo.c
index 634528b23d..1620aa428c 100644
--- a/lib/isc/unix/meminfo.c
+++ b/lib/isc/unix/meminfo.c
@@ -34,7 +34,14 @@ isc_meminfo_totalphys(void) {
 		return (size);
 #endif
 #if defined(_SC_PHYS_PAGES) && defined(_SC_PAGESIZE)
-	return ((size_t) (sysconf(_SC_PHYS_PAGES) * sysconf(_SC_PAGESIZE)));
-#endif
+	long pages = sysconf(_SC_PHYS_PAGES);
+	long pagesize = sysconf(_SC_PAGESIZE);
+
+	if (pages == -1 || pagesize == -1) {
+		return (0);
+	}
+
+	return ((size_t)pages * pagesize);
+#endif /* if defined(_SC_PHYS_PAGES) && defined(_SC_PAGESIZE) */
 	return (0);
 }