diff --git a/arch/s390/include/uapi/asm/ucontext.h b/arch/s390/include/uapi/asm/ucontext.h
index 200e06325c6a..3e077b2a4705 100644
--- a/arch/s390/include/uapi/asm/ucontext.h
+++ b/arch/s390/include/uapi/asm/ucontext.h
@@ -16,7 +16,9 @@ struct ucontext_extended {
 	struct ucontext  *uc_link;
 	stack_t		  uc_stack;
 	_sigregs	  uc_mcontext;
-	unsigned long	  uc_sigmask[2];
+	sigset_t	  uc_sigmask;
+	/* Allow for uc_sigmask growth.  Glibc uses a 1024-bit sigset_t.  */
+	unsigned char	  __unused[128 - sizeof(sigset_t)];
 	unsigned long	  uc_gprs_high[16];
 };
 
@@ -27,7 +29,9 @@ struct ucontext {
 	struct ucontext  *uc_link;
 	stack_t		  uc_stack;
 	_sigregs          uc_mcontext;
-	sigset_t	  uc_sigmask;	/* mask last for extensibility */
+	sigset_t	  uc_sigmask;
+	/* Allow for uc_sigmask growth.  Glibc uses a 1024-bit sigset_t.  */
+	unsigned char	  __unused[128 - sizeof(sigset_t)];
 };
 
 #endif /* !_ASM_S390_UCONTEXT_H */
diff --git a/arch/s390/kernel/compat_linux.h b/arch/s390/kernel/compat_linux.h
index 39ddfdb40ae8..70d4b7c4beaa 100644
--- a/arch/s390/kernel/compat_linux.h
+++ b/arch/s390/kernel/compat_linux.h
@@ -69,7 +69,9 @@ struct ucontext32 {
 	__u32			uc_link;	/* pointer */	
 	compat_stack_t		uc_stack;
 	_sigregs32		uc_mcontext;
-	compat_sigset_t		uc_sigmask;	/* mask last for extensibility */
+	compat_sigset_t		uc_sigmask;
+	/* Allow for uc_sigmask growth.  Glibc uses a 1024-bit sigset_t.  */
+	unsigned char		__unused[128 - sizeof(compat_sigset_t)];
 };
 
 struct stat64_emu31;