diff --git a/lib/libc/gen/readdir.c b/lib/libc/gen/readdir.c
--- a/lib/libc/gen/readdir.c
+++ b/lib/libc/gen/readdir.c
@@ -50,6 +50,7 @@
 	struct dirent *dp;
 	off_t initial_seek;
 	size_t initial_loc = 0;
+	ssize_t ret;
 
 	for (;;) {
 		if (dirp->dd_loc >= dirp->dd_size) {
@@ -61,11 +62,13 @@
 		}
 		if (dirp->dd_loc == 0 &&
 		    !(dirp->dd_flags & (__DTF_READALL | __DTF_SKIPREAD))) {
+			dirp->dd_size = 0;
 			initial_seek = dirp->dd_seek;
-			dirp->dd_size = _getdirentries(dirp->dd_fd,
+			ret = _getdirentries(dirp->dd_fd,
 			    dirp->dd_buf, dirp->dd_len, &dirp->dd_seek);
-			if (dirp->dd_size <= 0)
+			if (ret <= 0)
 				return (NULL);
+			dirp->dd_size = (size_t)ret;
 			_fixtelldir(dirp, initial_seek, initial_loc);
 		}
 		dirp->dd_flags &= ~__DTF_SKIPREAD;
diff --git a/lib/libc/tests/gen/opendir_test.c b/lib/libc/tests/gen/opendir_test.c
--- a/lib/libc/tests/gen/opendir_test.c
+++ b/lib/libc/tests/gen/opendir_test.c
@@ -46,6 +46,7 @@
 	ATF_CHECK_STREQ("subdir", ent->d_name);
 	ATF_CHECK_EQ(DT_DIR, ent->d_type);
 	ATF_CHECK(readdir(dirp) == NULL);
+	ATF_CHECK(readdir(dirp) == NULL);
 }
 
 ATF_TC(opendir_ok);
diff --git a/lib/libc/tests/gen/scandir_test.c b/lib/libc/tests/gen/scandir_test.c
--- a/lib/libc/tests/gen/scandir_test.c
+++ b/lib/libc/tests/gen/scandir_test.c
@@ -157,7 +157,7 @@
 {
 	char path[16];
 	struct dirent **namelist = NULL;
-	int fd, i, ret;
+	int fd, i;
 
 	ATF_REQUIRE_EQ(0, mkdir("dir", 0755));
 	for (i = 0; i < 1024; i++) {
@@ -170,9 +170,8 @@
 	scandir_error_count = 0;
 	scandir_error_fd = fd;
 	scandir_error_select_return = 0;
-	ret = fdscandir(fd, &namelist, scandir_error_select, NULL);
-	ATF_CHECK_EQ(-1, ret);
-	ATF_CHECK_ERRNO(EBADF, ret < 0);
+	ATF_CHECK_ERRNO(EBADF,
+	    fdscandir(fd, &namelist, scandir_error_select, NULL) < 0);
 	ATF_CHECK_EQ(NULL, namelist);
 
 	/* second pass, select everything */
@@ -180,9 +179,8 @@
 	scandir_error_count = 0;
 	scandir_error_fd = fd;
 	scandir_error_select_return = 1;
-	ret = fdscandir(fd, &namelist, scandir_error_select, NULL);
-	ATF_CHECK_EQ(-1, ret);
-	ATF_CHECK_ERRNO(EBADF, ret < 0);
+	ATF_CHECK_ERRNO(EBADF,
+	    fdscandir(fd, &namelist, scandir_error_select, NULL) < 0);
 	ATF_CHECK_EQ(NULL, namelist);
 }