diff --git a/Changes b/Changes
index 90f8a11dc..15d26d075 100644
--- a/Changes
+++ b/Changes
@@ -37,6 +37,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ****  Fix float-conversion warning, bug1229. [Robert Henry]
 
+****  Fix MacOS portability, bug1230. [Jeff Bush]
+
 
 * Verilator 3.912 2017-09-23
 
diff --git a/configure.ac b/configure.ac
index 3fd566ec6..c95c5524b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -222,6 +222,9 @@ _MY_CXX_CHECK_OPT(CFG_CXXFLAGS_NO_UNUSED,-Wno-shadow)
 AC_SUBST(CFG_CXXFLAGS_NO_UNUSED)
 
 # Checks for library functions.
+AC_CHECK_MEMBER([struct stat.st_mtim.tv_nsec],
+    [AC_DEFINE([HAVE_STAT_NSEC],[1],[Define if struct stat has st_mtim.tv_nsec.])],
+    [], [#include <sys/stat.h>])
 
 # Checks for system services
 
diff --git a/src/V3File.cpp b/src/V3File.cpp
index 8e9791e5b..0c9240e03 100644
--- a/src/V3File.cpp
+++ b/src/V3File.cpp
@@ -34,7 +34,7 @@
 # define INFILTER_PIPE  // Allow pipe filtering.  Needs fork()
 #endif
 
-#ifdef st_mtime // Linux 2.6
+#ifdef HAVE_STAT_NSEC // i.e. Linux 2.6, from configure
 # define VL_STAT_CTIME_NSEC(stat) ((stat).st_ctim.tv_nsec) // Nanoseconds
 # define VL_STAT_MTIME_NSEC(stat) ((stat).st_mtim.tv_nsec) // Nanoseconds
 #else
diff --git a/src/config_build.h.in b/src/config_build.h.in
index ccfc1e553..49efaad79 100644
--- a/src/config_build.h.in
+++ b/src/config_build.h.in
@@ -68,8 +68,13 @@
 
 using namespace std;
 
+//**********************************************************************
+//**** Configure-discovered library options
+
+// Define if struct stat has st_mtim.tv_nsec (from configure)
+#undef HAVE_STAT_NSEC
+
 //**********************************************************************
 //**** OS and compiler specifics
 
 #include "verilatedos.h"
-