diff --git a/Makefile.conf b/Makefile.conf
index c1fadb4e..b4a221cc 100644
--- a/Makefile.conf
+++ b/Makefile.conf
@@ -100,8 +100,11 @@ ifeq ($(BUILD_FOR),OS/390)
     CFLAGS+= -I/usr/include
     CFLAGS+= -DZOS -D_XOPEN_SOURCE=600 -D_POSIX_C_SOURCE=200112L -qlanglvl=NOLIBEXT
 else ifeq ($(BUILD_FOR),Linux)
+    CFLAGS+= -DUNIX 
     CFLAGS+=-fPIC -fstrict-aliasing -fdiagnostics-color=auto
 else ifeq ($(BUILD_FOR),Darwin)
+    CFLAGS+= -DUNIX 
+    CFLAGS+= -DDARWIN 
     CFLAGS+=-pthread -fPIC -fstrict-aliasing -fcolor-diagnostics
 endif
 
diff --git a/src/Makefile b/src/Makefile
index 0eb3766e..b11db044 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -128,7 +128,8 @@ HEADERS_TO_INSTALL = \
   timestamp.h identity_list.h bloblist.h stringpair.h message.h mime.h group.h \
   cryptotech.h sync_api.h pEp_string.h openpgp_compat.h engine_sql.h \
   labeled_int_list.h key_reset.h base64.h sync_codec.h distribution_codec.h \
-  storage_codec.h status_to_string.h keyreset_command.h platform.h platform_unix.h \
+  storage_codec.h status_to_string.h keyreset_command.h platform.h \
+  platform_unix.h platform_windows.h platform_zos.h \
   transport.h growing_buf.h $(wildcard ../asn.1/*.h)
 
 # CAVEAT:
diff --git a/src/platform.h b/src/platform.h
index 7d0bb3fd..bcef6e84 100644
--- a/src/platform.h
+++ b/src/platform.h
@@ -11,10 +11,14 @@
 extern "C" {
 #endif
 
-#ifdef _WIN32
-#include "platform_windows.h"
+#if defined (_WIN32)
+# include "platform_windows.h"
+#elif defined (UNIX)
+# include "platform_unix.h"
+#elif defined (ZOS)
+# include "platform_zos.h"
 #else
-#include "platform_unix.h"
+# error "unknown platform"
 #endif
 
 #ifdef __cplusplus
diff --git a/src/platform_zos.c b/src/platform_zos.c
new file mode 100644
index 00000000..32bc3c6a
--- /dev/null
+++ b/src/platform_zos.c
@@ -0,0 +1,15 @@
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
+/* Include the entire useful part of this compilation unit within a CPP
+   conditional, so that the entire file expands to nothing if this is not
+   the platform it is used on. */
+#ifdef ZOS
+
+#include "pEpEngine.h"
+#include "platform_zos.h"
+#include "dynamic_api.h"
+
+/* Nothing useful here at this time. */
+
+#endif // #ifdef ZOS
diff --git a/src/platform_zos.h b/src/platform_zos.h
new file mode 100644
index 00000000..29088acc
--- /dev/null
+++ b/src/platform_zos.h
@@ -0,0 +1,32 @@
+/**
+ * @file    platform_zos.h
+ * @brief   z/OS platform-specific implementation details
+ * @license GNU General Public License 3.0 - see LICENSE.txt
+ */
+
+#ifndef PEP_PLATFORM_ZOS_H
+#define PEP_PLATFORM_ZOS_H
+
+#if ! defined (ZOS)
+# error "this header should only ever be included on z/OS"
+#endif
+
+/* Workaround standard header problems. */
+
+#ifdef __cplusplus
+# undef _EXT
+# define _NO_EXT
+#endif
+#include_next <stdlib.h>
+
+#ifndef __cplusplus
+char * stpcpy (char *dst, const char *src);
+char * strndup (const char *s, size_t n);
+size_t strnlen (const char *s, size_t maxlen);
+#endif
+#include <strings.h>
+
+#include_next <string.h>
+
+
+#endif // #ifndef PEP_PLATFORM_ZOS_H
diff --git a/src/stdlib.h b/src/stdlib.h
deleted file mode 100644
index 5370b1c7..00000000
--- a/src/stdlib.h
+++ /dev/null
@@ -1,8 +0,0 @@
-#ifdef ZOS
-#ifdef __cplusplus
-#undef _EXT
-#define _NO_EXT
-#endif
-#endif
-
-#include_next <stdlib.h>
diff --git a/src/string.h b/src/string.h
deleted file mode 100644
index ac2323f5..00000000
--- a/src/string.h
+++ /dev/null
@@ -1,10 +0,0 @@
-#ifdef ZOS
-#ifndef __cplusplus
-char * stpcpy (char *dst, const char *src);
-char * strndup (const char *s, size_t n);
-size_t strnlen (const char *s, size_t maxlen);
-#endif
-#include <strings.h>
-#endif
-
-#include_next <string.h>