diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index b534e95450b..49a7e396ccf 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,7 @@
+2018-08-08  Tom Tromey  <tom@tromey.com>
+
+	* unittests/scoped_mmap-selftests.c: Check result of "write".
+
 2018-08-08  Jim Wilson  <jimw@sifive.com>
 
 	* riscv-tdep.c (enum opcode): Add jump, branch, lr, and sc opcodes.
diff --git a/gdb/unittests/scoped_mmap-selftests.c b/gdb/unittests/scoped_mmap-selftests.c
index d70a56a1862..e9d4afdffc5 100644
--- a/gdb/unittests/scoped_mmap-selftests.c
+++ b/gdb/unittests/scoped_mmap-selftests.c
@@ -91,7 +91,7 @@ test_normal ()
   int fd = mkstemp (filename);
   SELF_CHECK (fd >= 0);
 
-  write (fd, "Hello!", 7);
+  SELF_CHECK (write (fd, "Hello!", 7) == 7);
   close (fd);
 
   gdb::unlinker unlink_test_file (filename);