diff --git a/NEWS b/NEWS
index 6c588593..3ea553f9 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,9 @@ Noteworthy changes in release ?.?? (????-??-??)
 * Improvements
   * Enhanced decoding of sched_setattr syscall.
 
+* Bug fixes
+  * Fixed decoding of flags argument of preadv2 and pwritev2 syscalls on x32.
+
 Noteworthy changes in release 4.16 (2017-02-14)
 ===============================================
 
diff --git a/io.c b/io.c
index c41b66fa..a4f6b8e8 100644
--- a/io.c
+++ b/io.c
@@ -224,11 +224,6 @@ SYS_FUNC(preadv)
 	return do_preadv(tcp, -1);
 }
 
-SYS_FUNC(preadv2)
-{
-	return do_preadv(tcp, 5);
-}
-
 static int
 do_pwritev(struct tcb *tcp, const int flags_arg)
 {
@@ -253,9 +248,29 @@ SYS_FUNC(pwritev)
 	return do_pwritev(tcp, -1);
 }
 
+/*
+ * x32 is the only architecture where preadv2 takes 5 arguments
+ * instead of 6, see preadv64v2 in kernel sources.
+ * Likewise, x32 is the only architecture where pwritev2 takes 5 arguments
+ * instead of 6, see pwritev64v2 in kernel sources.
+ */
+
+#if defined X86_64
+# define PREADV2_PWRITEV2_FLAGS_ARG_NO (current_personality == 2 ? 4 : 5)
+#elif defined X32
+# define PREADV2_PWRITEV2_FLAGS_ARG_NO (current_personality == 0 ? 4 : 5)
+#else
+# define PREADV2_PWRITEV2_FLAGS_ARG_NO 5
+#endif
+
+SYS_FUNC(preadv2)
+{
+	return do_preadv(tcp, PREADV2_PWRITEV2_FLAGS_ARG_NO);
+}
+
 SYS_FUNC(pwritev2)
 {
-	return do_pwritev(tcp, 5);
+	return do_pwritev(tcp, PREADV2_PWRITEV2_FLAGS_ARG_NO);
 }
 
 #include "xlat/splice_flags.h"
diff --git a/linux/x32/syscallent.h b/linux/x32/syscallent.h
index 0cda1a65..5f187642 100644
--- a/linux/x32/syscallent.h
+++ b/linux/x32/syscallent.h
@@ -369,5 +369,5 @@
 [543] = { 2,	CST|TM,		SEN(io_setup),			"io_setup"		},
 [544] = { 3,	CST,		SEN(io_submit),			"io_submit"		},
 [545] = { 5,	CST|TD|TF|TP|SE|SI,	SEN(execveat),		"execveat"		},
-[546] = { 6,	TD,		SEN(preadv2),			"preadv2"		},
-[547] = { 6,	TD,		SEN(pwritev2),			"pwritev2"		},
+[546] = { 5,	TD,		SEN(preadv2),			"preadv2"		},
+[547] = { 5,	TD,		SEN(pwritev2),			"pwritev2"		},
diff --git a/tests/preadv2-pwritev2.c b/tests/preadv2-pwritev2.c
index f7c46c0a..bcf8b77d 100644
--- a/tests/preadv2-pwritev2.c
+++ b/tests/preadv2-pwritev2.c
@@ -181,26 +181,45 @@ int
 main(void)
 {
 	const kernel_ulong_t vlen = (kernel_ulong_t) 0xfac1fed2dad3bef4ULL;
-	const unsigned long long pos = 0xfac5fed6dad7bef8;
+	const unsigned long long pos = 0x7ac5fed6dad7bef8;
 	const kernel_ulong_t pos_l = (kernel_ulong_t) pos;
-	const kernel_ulong_t pos_h =
-		(sizeof(kernel_ulong_t) == sizeof(long long)) ?
-		(kernel_ulong_t) 0xbadc0deddeadbeefULL : 0xfac5fed6UL;
-	int test_dumpio = 1;
+	long rc;
+	int test_dumpio;
 
 	tprintf("%s", "");
 
-	syscall(__NR_preadv2, -1, NULL, vlen, pos_l, pos_h, 1);
-	if (ENOSYS == errno)
-		test_dumpio = 0;
-	tprintf("preadv2(-1, NULL, %lu, %lld, RWF_HIPRI) = -1 %s (%m)\n",
-		(unsigned long) vlen, pos, errno2name());
+#if defined __x86_64__ && defined __ILP32__
+	/*
+	 * x32 is the only architecture where preadv2 takes 5 arguments,
+	 * see preadv64v2 in kernel sources.
+	 */
+	rc = syscall(__NR_preadv2, -1, NULL, vlen, pos_l, 1);
+#else
+	const kernel_ulong_t pos_h =
+		(sizeof(pos_l) == sizeof(pos)) ?
+		(kernel_ulong_t) 0xbadc0deddeadbeefULL :
+		(kernel_ulong_t) (pos >> 32);
+	rc = syscall(__NR_preadv2, -1, NULL, vlen, pos_l, pos_h, 1);
+#endif
+	if (rc != -1 || (ENOSYS != errno && EBADF != errno))
+		perror_msg_and_fail("preadv2");
+	test_dumpio = EBADF == errno;
+	tprintf("preadv2(-1, NULL, %lu, %lld, RWF_HIPRI) = %s\n",
+		(unsigned long) vlen, pos, sprintrc(rc));
 
-	syscall(__NR_pwritev2, -1, NULL, vlen, pos_l, pos_h, 1);
-	if (ENOSYS == errno)
-		test_dumpio = 0;
-	tprintf("pwritev2(-1, NULL, %lu, %lld, RWF_HIPRI) = -1 %s (%m)\n",
-		(unsigned long) vlen, pos, errno2name());
+#if defined __x86_64__ && defined __ILP32__
+	/*
+	 * x32 is the only architecture where pwritev2 takes 5 arguments,
+	 * see pwritev64v2 in kernel sources.
+	 */
+	rc = syscall(__NR_pwritev2, -1, NULL, vlen, pos_l, 1);
+#else
+	rc = syscall(__NR_pwritev2, -1, NULL, vlen, pos_l, pos_h, 1);
+#endif
+	if (rc != -1 || (ENOSYS != errno && EBADF != errno))
+		perror_msg_and_fail("pwritev2");
+	tprintf("pwritev2(-1, NULL, %lu, %lld, RWF_HIPRI) = %s\n",
+		(unsigned long) vlen, pos, sprintrc(rc));
 
 	if (test_dumpio)
 		dumpio();