diff --git a/README.md b/README.md
index 1377fe9..c91e0a3 100644
--- a/README.md
+++ b/README.md
@@ -25,7 +25,7 @@ Adding support for new architectures is easy, but you need to know assembly lang
 |      ppc     | ✓             | ✓       |                       |
 |     ppc64    | ✓             | ✓       |                       |
 |    riscv64   | ✓             |         |                       |
-|     s390x    | ✓             |         |                       |
+|     s390x    | ✓             |         | ✓                     |
 |      x86     | ✓             |         | ✓                     |
 |    x86_64    | ✓             |         | ✓                     |
 
diff --git a/arch/s390x/freestanding/bits.h b/arch/s390x/freestanding/bits.h
new file mode 100644
index 0000000..bce841c
--- /dev/null
+++ b/arch/s390x/freestanding/bits.h
@@ -0,0 +1,41 @@
+#ifndef LIBUCONTEXT_BITS_H
+#define LIBUCONTEXT_BITS_H
+
+typedef unsigned long libucontext_greg_t, libucontext_gregset_t[27];
+
+typedef struct {
+	unsigned long mask;
+	unsigned long addr;
+} libucontext_psw_t;
+
+typedef union {
+	double d;
+	float f;
+} libucontext_fpreg_t;
+
+typedef struct {
+	unsigned fpc;
+	libucontext_fpreg_t fprs[16];
+} libucontext_fpregset_t;
+
+typedef struct {
+	libucontext_psw_t psw;
+	unsigned long gregs[16];
+	unsigned aregs[16];
+	libucontext_fpregset_t fpregs;
+} libucontext_mcontext_t;
+
+typedef struct {
+	void *ss_sp;
+	int ss_flags;
+	size_t ss_size;
+} libucontext_stack_t;
+
+typedef struct libucontext_ucontext {
+	unsigned long uc_flags;
+	struct libucontext_ucontext *uc_link;
+	libucontext_stack_t uc_stack;
+	libucontext_mcontext_t uc_mcontext;
+} libucontext_ucontext_t;
+
+#endif
diff --git a/arch/s390x/makecontext.c b/arch/s390x/makecontext.c
index 726bd9c..e74c6f3 100644
--- a/arch/s390x/makecontext.c
+++ b/arch/s390x/makecontext.c
@@ -21,7 +21,7 @@
 
 
 extern void libucontext_trampoline(void);
-extern int libucontext_setcontext(const ucontext_t *ucp);
+extern int libucontext_setcontext(const libucontext_ucontext_t *ucp);
 
 
 void