diff --git a/CHANGELOG.md b/CHANGELOG.md
index 68903e0a..ec45d948 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,8 +1,9 @@
 # UNRELEASED
 
-  * Fix the bcrypt "wrap-around" bug. It affects passwords with lengths >= 255. 
+  * Fix the bcrypt "wrap-around" bug. It affects passwords with lengths >= 255.
     It is uncommon but it's a bug nevertheless. Previous attempts to fix the bug
     was unsuccessful.
+  * Experimental support for z/OS
 
 # 4.0.1 (2020-02-27)
 
diff --git a/binding.gyp b/binding.gyp
index 39536f48..986d7107 100644
--- a/binding.gyp
+++ b/binding.gyp
@@ -34,8 +34,13 @@
             'GCC_ENABLE_CPP_EXCEPTIONS': 'YES',
             'GCC_SYMBOLS_PRIVATE_EXTERN': 'YES', # -fvisibility=hidden
           }
-        }]
-      ]
+        }],
+        [ 'OS=="zos"', {
+          'cflags': [
+            '-qascii',
+          ],
+        }],
+      ],
     },
     {
       "target_name": "action_after_build",
diff --git a/src/node_blf.h b/src/node_blf.h
index 5793ee04..2aa58e72 100644
--- a/src/node_blf.h
+++ b/src/node_blf.h
@@ -60,6 +60,14 @@
 #  endif
   typedef LONG_PTR SSIZE_T;
   typedef SSIZE_T ssize_t;
+/* z/OS compatibility */
+#endif
+
+#ifdef __MVS__
+typedef unsigned char u_int8_t;
+typedef unsigned short u_int16_t;
+typedef unsigned int u_int32_t;
+typedef unsigned long long u_int64_t;
 #endif
 
 #define BCRYPT_VERSION '2'