diff --git a/addon.gypi b/addon.gypi
index 9327b0d722..b3489e39bd 100644
--- a/addon.gypi
+++ b/addon.gypi
@@ -103,6 +103,11 @@
           '-Wl,-bimport:<(node_exp_file)'
         ],
       }],
+      [ 'OS=="os400"', {
+        'ldflags': [
+          '-Wl,-bimport:<(node_exp_file)'
+        ],
+      }],
       [ 'OS=="zos"', {
         'cflags': [
           '-q64',
diff --git a/gyp/pylib/gyp/common.py b/gyp/pylib/gyp/common.py
index 9213fcc5e8..0847cdabc7 100644
--- a/gyp/pylib/gyp/common.py
+++ b/gyp/pylib/gyp/common.py
@@ -454,6 +454,8 @@ def GetFlavor(params):
         return "aix"
     if sys.platform.startswith(("os390", "zos")):
         return "zos"
+    if sys.platform == "os400":
+        return "os400"
 
     return "linux"
 
@@ -463,9 +465,13 @@ def CopyTool(flavor, out_path, generator_flags={}):
   to |out_path|."""
     # aix and solaris just need flock emulation. mac and win use more complicated
     # support scripts.
-    prefix = {"aix": "flock", "solaris": "flock", "mac": "mac", "win": "win"}.get(
-        flavor, None
-    )
+    prefix = {
+        "aix": "flock",
+        "os400": "flock",
+        "solaris": "flock",
+        "mac": "mac",
+        "win": "win",
+    }.get(flavor, None)
     if not prefix:
         return
 
diff --git a/gyp/pylib/gyp/flock_tool.py b/gyp/pylib/gyp/flock_tool.py
index 1cb9815263..0754aff26f 100755
--- a/gyp/pylib/gyp/flock_tool.py
+++ b/gyp/pylib/gyp/flock_tool.py
@@ -41,7 +41,7 @@ def ExecFlock(self, lockfile, *cmd_list):
         # with EBADF, that's why we use this F_SETLK
         # hack instead.
         fd = os.open(lockfile, os.O_WRONLY | os.O_NOCTTY | os.O_CREAT, 0o666)
-        if sys.platform.startswith("aix"):
+        if sys.platform.startswith("aix") or sys.platform == "os400":
             # Python on AIX is compiled with LARGEFILE support, which changes the
             # struct size.
             op = struct.pack("hhIllqq", fcntl.F_WRLCK, 0, 0, 0, 0, 0, 0)
diff --git a/gyp/test_gyp.py b/gyp/test_gyp.py
index 9ba264170f..b7bb956b8e 100755
--- a/gyp/test_gyp.py
+++ b/gyp/test_gyp.py
@@ -116,6 +116,7 @@ def main(argv=None):
     else:
         format_list = {
             "aix5": ["make"],
+            "os400": ["make"],
             "freebsd7": ["make"],
             "freebsd8": ["make"],
             "openbsd5": ["make"],
diff --git a/lib/build.js b/lib/build.js
index c2388fb348..f607c7279e 100644
--- a/lib/build.js
+++ b/lib/build.js
@@ -11,6 +11,8 @@ function build (gyp, argv, callback) {
   var platformMake = 'make'
   if (process.platform === 'aix') {
     platformMake = 'gmake'
+  } else if (process.platform === 'os400') {
+    platformMake = 'gmake'
   } else if (process.platform.indexOf('bsd') !== -1) {
     platformMake = 'gmake'
   } else if (win && argv.length > 0) {
diff --git a/lib/configure.js b/lib/configure.js
index 17a6487fa9..4371efe274 100644
--- a/lib/configure.js
+++ b/lib/configure.js
@@ -153,12 +153,12 @@ function configure (gyp, argv, callback) {
     // For AIX and z/OS we need to set up the path to the exports file
     // which contains the symbols needed for linking.
     var nodeExpFile
-    if (process.platform === 'aix' || process.platform === 'os390') {
-      var ext = process.platform === 'aix' ? 'exp' : 'x'
+    if (process.platform === 'aix' || process.platform === 'os390' || process.platform === 'os400') {
+      var ext = process.platform === 'os390' ? 'x' : 'exp'
       var nodeRootDir = findNodeDirectory()
       var candidates
 
-      if (process.platform === 'aix') {
+      if (process.platform === 'aix' || process.platform === 'os400') {
         candidates = [
           'include/node/node',
           'out/Release/node',
@@ -215,7 +215,7 @@ function configure (gyp, argv, callback) {
       argv.push('-Dlibrary=shared_library')
       argv.push('-Dvisibility=default')
       argv.push('-Dnode_root_dir=' + nodeDir)
-      if (process.platform === 'aix' || process.platform === 'os390') {
+      if (process.platform === 'aix' || process.platform === 'os390' || process.platform === 'os400') {
         argv.push('-Dnode_exp_file=' + nodeExpFile)
       }
       argv.push('-Dnode_gyp_dir=' + nodeGypDir)
diff --git a/test/test-find-node-directory.js b/test/test-find-node-directory.js
index f1380d162a..fa6223c65d 100644
--- a/test/test-find-node-directory.js
+++ b/test/test-find-node-directory.js
@@ -4,7 +4,7 @@ const test = require('tap').test
 const path = require('path')
 const findNodeDirectory = require('../lib/find-node-directory')
 
-const platforms = ['darwin', 'freebsd', 'linux', 'sunos', 'win32', 'aix']
+const platforms = ['darwin', 'freebsd', 'linux', 'sunos', 'win32', 'aix', 'os400']
 
 // we should find the directory based on the directory
 // the script is running in and it should match the layout