diff --git a/mem.c b/mem.c
index 2ca89548..1f37826f 100644
--- a/mem.c
+++ b/mem.c
@@ -96,15 +96,15 @@ SYS_FUNC(old_mmap)
 	long u_arg[6];
 # if defined AARCH64 || defined X86_64
 	/* We are here only in a 32-bit personality. */
-	int i;
-	unsigned narrow_arg[6];
-	if (umoven(tcp, tcp->u_arg[0], sizeof(narrow_arg), narrow_arg) == -1)
-		return 0;
-	for (i = 0; i < 6; ++i)
-		u_arg[i] = (unsigned long) narrow_arg[i];
+	unsigned int narrow_arg[6];
+	if (umove_or_printaddr(tcp, tcp->u_arg[0], &narrow_arg))
+		return RVAL_DECODED | RVAL_HEX;
+	unsigned int i;
+	for (i = 0; i < 6; i++)
+		u_arg[i] = narrow_arg[i];
 # else
-	if (umoven(tcp, tcp->u_arg[0], sizeof(u_arg), u_arg) == -1)
-		return 0;
+	if (umove_or_printaddr(tcp, tcp->u_arg[0], &u_arg))
+		return RVAL_DECODED | RVAL_HEX;
 # endif
 	print_mmap(tcp, u_arg, (unsigned long) u_arg[5]);
 
diff --git a/tests/old_mmap.c b/tests/old_mmap.c
index c9e802de..97051db9 100644
--- a/tests/old_mmap.c
+++ b/tests/old_mmap.c
@@ -51,6 +51,9 @@
 int
 main(void)
 {
+	long rc = syscall(__NR_mmap, 0);
+	printf("mmap(NULL) = %ld %s (%m)\n", rc, errno2name());
+
 	const unsigned int args1_c[6] = {
 		0xdeadbeef,		/* addr */
 		0xfacefeed,		/* len */
@@ -70,7 +73,7 @@ main(void)
 	};
 	void *args = tail_memdup(args1_c, sizeof(args1_c));
 
-	long rc = syscall(__NR_mmap, args);
+	rc = syscall(__NR_mmap, args);
 	printf("mmap(%#x, %u, PROT_READ|PROT_EXEC, MAP_FILE|MAP_FIXED"
 	       ", %d, %#x) = %ld %s (%m)\n",
 	       args1_c[0], args1_c[1], args1_c[4], args1_c[5],
diff --git a/tests/old_mmap.test b/tests/old_mmap.test
index 07fb44a2..af776ff7 100755
--- a/tests/old_mmap.test
+++ b/tests/old_mmap.test
@@ -3,4 +3,4 @@
 # Check decoding of "old mmap" edition of mmap syscall.
 
 . "${srcdir=.}/init.sh"
-run_strace_match_diff -e trace=mmap
+run_strace_match_diff -a11 -e trace=mmap