diff --git a/Makefile b/Makefile
index 7b6db1f8..9de29ebe 100644
--- a/Makefile
+++ b/Makefile
@@ -60,6 +60,7 @@ INSTALL_TARGETS := install-headers install-libs
 ifeq ($(LIBPHOENIX_PIC), y)
 CFLAGS += $(TARGET_PIC_FLAG)
 ifeq ($(LIBPHOENIX_SHARED), y)
+CPPFLAGS += -DLIBPHOENIX_SHARED
 include shared.mk
 endif
 endif
diff --git a/errno/errno.c b/errno/errno.c
index fccd3468..e0bc9d01 100644
--- a/errno/errno.c
+++ b/errno/errno.c
@@ -19,6 +19,12 @@
 #include <arch.h>
 
 
+#ifdef LIBPHOENIX_SHARED
+/* FIXME: TLS is not yet supported by dynamic linker. */
+#undef __LIBPHOENIX_ARCH_TLS_SUPPORTED
+#endif
+
+
 #ifdef __LIBPHOENIX_ARCH_TLS_SUPPORTED
 
 static __thread int __errno_tls;