diff --git a/tools/include/nolibc/arch-s390.h b/tools/include/nolibc/arch-s390.h
index 2ec13d8b9a2d..f9ab83a219b8 100644
--- a/tools/include/nolibc/arch-s390.h
+++ b/tools/include/nolibc/arch-s390.h
@@ -10,6 +10,7 @@
 
 #include "compiler.h"
 #include "crt.h"
+#include "std.h"
 
 /* Syscalls for s390:
  *   - registers are 64-bit
diff --git a/tools/include/nolibc/compiler.h b/tools/include/nolibc/compiler.h
index 9bc6a706a332..fa1f547e7f13 100644
--- a/tools/include/nolibc/compiler.h
+++ b/tools/include/nolibc/compiler.h
@@ -32,4 +32,10 @@
 #  define __no_stack_protector __attribute__((__optimize__("-fno-stack-protector")))
 #endif /* __nolibc_has_attribute(no_stack_protector) */
 
+#if __nolibc_has_attribute(fallthrough)
+#  define __nolibc_fallthrough do { } while (0); __attribute__((fallthrough))
+#else
+#  define __nolibc_fallthrough do { } while (0)
+#endif /* __nolibc_has_attribute(fallthrough) */
+
 #endif /* _NOLIBC_COMPILER_H */
diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
index c968dbbc4ef8..3892034198dd 100644
--- a/tools/include/nolibc/stdio.h
+++ b/tools/include/nolibc/stdio.h
@@ -15,6 +15,7 @@
 #include "stdarg.h"
 #include "stdlib.h"
 #include "string.h"
+#include "compiler.h"
 
 #ifndef EOF
 #define EOF (-1)
@@ -264,7 +265,7 @@ int vfprintf(FILE *stream, const char *fmt, va_list args)
 				case 'p':
 					*(out++) = '0';
 					*(out++) = 'x';
-					/* fall through */
+					__nolibc_fallthrough;
 				default: /* 'x' and 'p' above */
 					u64toh_r(v, out);
 					break;
diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile
index 8de98ea7af80..e92e0b885861 100644
--- a/tools/testing/selftests/nolibc/Makefile
+++ b/tools/testing/selftests/nolibc/Makefile
@@ -130,9 +130,9 @@ QEMU_ARGS_ppc        = -M g3beige -append "console=ttyS0 panic=-1 $(TEST:%=NOLIB
 QEMU_ARGS_ppc64      = -M powernv -append "console=hvc0 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
 QEMU_ARGS_ppc64le    = -M powernv -append "console=hvc0 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
 QEMU_ARGS_riscv      = -M virt -append "console=ttyS0 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
-QEMU_ARGS_s390       = -M s390-ccw-virtio -m 1G -append "console=ttyS0 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
+QEMU_ARGS_s390       = -M s390-ccw-virtio -append "console=ttyS0 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
 QEMU_ARGS_loongarch  = -M virt -append "console=ttyS0,115200 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
-QEMU_ARGS            = $(QEMU_ARGS_$(XARCH)) $(QEMU_ARGS_BIOS) $(QEMU_ARGS_EXTRA)
+QEMU_ARGS            = -m 1G $(QEMU_ARGS_$(XARCH)) $(QEMU_ARGS_BIOS) $(QEMU_ARGS_EXTRA)
 
 # OUTPUT is only set when run from the main makefile, otherwise
 # it defaults to this nolibc directory.