diff --git a/tests/sys_vfs_test.cpp b/tests/sys_vfs_test.cpp
index a521967..f82f505 100644
--- a/tests/sys_vfs_test.cpp
+++ b/tests/sys_vfs_test.cpp
@@ -44,12 +44,26 @@
   Check(sb);
 }
 
+TEST(sys_vfs, statfs_failure) {
+  struct statfs sb;
+  errno = 0;
+  ASSERT_EQ(-1, statfs("/does-not-exist", &sb));
+  ASSERT_EQ(ENOENT, errno);
+}
+
 TEST(sys_vfs, statfs64) {
   struct statfs64 sb;
   ASSERT_EQ(0, statfs64("/proc", &sb));
   Check(sb);
 }
 
+TEST(sys_vfs, statfs64_failure) {
+  struct statfs64 sb;
+  errno = 0;
+  ASSERT_EQ(-1, statfs64("/does-not-exist", &sb));
+  ASSERT_EQ(ENOENT, errno);
+}
+
 TEST(sys_vfs, fstatfs) {
   struct statfs sb;
   int fd = open("/proc", O_RDONLY);
@@ -58,6 +72,13 @@
   Check(sb);
 }
 
+TEST(sys_vfs, fstatfs_failure) {
+  struct statfs sb;
+  errno = 0;
+  ASSERT_EQ(-1, fstatfs(-1, &sb));
+  ASSERT_EQ(EBADF, errno);
+}
+
 TEST(sys_vfs, fstatfs64) {
   struct statfs64 sb;
   int fd = open("/proc", O_RDONLY);
@@ -65,3 +86,10 @@
   close(fd);
   Check(sb);
 }
+
+TEST(sys_vfs, fstatfs64_failure) {
+  struct statfs sb;
+  errno = 0;
+  ASSERT_EQ(-1, fstatfs(-1, &sb));
+  ASSERT_EQ(EBADF, errno);
+}