diff --git a/src/include/platform.h b/src/include/platform.h
index f8f75f0d..6433a2bf 100644
--- a/src/include/platform.h
+++ b/src/include/platform.h
@@ -36,6 +36,13 @@
 
 #include "MHD_config.h"
 
+#ifndef BUILDING_MHD_LIB
+#ifdef _MHD_EXTERN
+#undef _MHD_EXTERN
+#endif /* _MHD_EXTERN */
+#define _MHD_EXTERN extern
+#endif /* BUILDING_MHD_LIB */
+
 #define _XOPEN_SOURCE_EXTENDED  1
 #if OS390
 #define _OPEN_THREADS
diff --git a/src/microhttpd/Makefile.am b/src/microhttpd/Makefile.am
index 61d2109d..02153a06 100644
--- a/src/microhttpd/Makefile.am
+++ b/src/microhttpd/Makefile.am
@@ -20,6 +20,9 @@ libmicrohttpd_la_SOURCES = \
   internal.c internal.h \
   memorypool.c memorypool.h \
   response.c response.h
+libmicrohttpd_la_CPPFLAGS = \
+  $(AM_CPPFLAGS) \
+  -DBUILDING_MHD_LIB=1
 libmicrohttpd_la_LDFLAGS = \
   $(MHD_LIB_LDFLAGS) \
   -version-info @LIB_VERSION_CURRENT@:@LIB_VERSION_REVISION@:@LIB_VERSION_AGE@
diff --git a/src/microspdy/Makefile.am b/src/microspdy/Makefile.am
index 3a343ddc..52929ee2 100644
--- a/src/microspdy/Makefile.am
+++ b/src/microspdy/Makefile.am
@@ -29,6 +29,10 @@ libmicrospdy_la_SOURCES = \
 libmicrospdy_la_LDFLAGS = \
   $(SPDY_LIB_LDFLAGS) 
 
+libmicrospdy_la_CPPFLAGS = \
+  $(AM_CPPFLAGS) \
+  -DBUILDING_MHD_LIB=1
+
 libmicrospdy_la_CFLAGS = -Wextra \
   $(SPDY_LIB_CFLAGS)