diff --git a/node.gypi b/node.gypi
index 559330fba8b1ca..64250ed19837e4 100644
--- a/node.gypi
+++ b/node.gypi
@@ -84,6 +84,9 @@
     }, { # POSIX
       'defines': [ '__POSIX__' ],
     }],
+    [ 'OS=="aix" or OS=="os400"', {
+      'cflags': [ '-mcpu=power9' ],
+    }],
     [ 'node_enable_d8=="true"', {
       'dependencies': [ 'tools/v8_gypfiles/d8.gyp:d8' ],
     }],
diff --git a/tools/v8_gypfiles/toolchain.gypi b/tools/v8_gypfiles/toolchain.gypi
index e614c39a6b53b9..b11be560e966e6 100644
--- a/tools/v8_gypfiles/toolchain.gypi
+++ b/tools/v8_gypfiles/toolchain.gypi
@@ -330,7 +330,7 @@
         'conditions': [
           ['OS=="aix" or OS=="os400"', {
             # Work around AIX ceil, trunc and round oddities.
-            'cflags': [ '-mcpu=power5+ -mfprnd' ],
+            'cflags': [ '-mcpu=power9 -mfprnd' ],
           }],
           ['OS=="aix" or OS=="os400"', {
             # Work around AIX assembler popcntb bug.