diff --git a/lib/libc/locale/collate.c b/lib/libc/locale/collate.c
--- a/lib/libc/locale/collate.c
+++ b/lib/libc/locale/collate.c
@@ -68,6 +68,10 @@
 	{{0}, "C"}, 1, 0, 0, 0
 };
 
+struct xlocale_collate __xlocale_CU8_collate = {
+	{{0}, "C"}, 1, 0, 0, 0
+};
+
 static int
 __collate_load_tables_l(const char *encoding, struct xlocale_collate *table);
 
@@ -84,10 +88,11 @@
 void *
 __collate_load(const char *encoding, __unused locale_t unused)
 {
-	if (strcmp(encoding, "C") == 0 || strcmp(encoding, "POSIX") == 0 ||
-	    strncmp(encoding, "C.", 2) == 0) {
+	if (strcmp(encoding, "C") == 0 || strcmp(encoding, "POSIX") == 0)
 		return (&__xlocale_C_collate);
-	}
+	else if (strncmp(encoding, "C.", 2) == 0)
+		return (&__xlocale_CU8_collate);
+
 	struct xlocale_collate *table = calloc(sizeof(struct xlocale_collate),
 	    1);
 	if (table == NULL)
diff --git a/lib/libc/tests/locale/Makefile b/lib/libc/tests/locale/Makefile
--- a/lib/libc/tests/locale/Makefile
+++ b/lib/libc/tests/locale/Makefile
@@ -13,6 +13,7 @@
 ATF_TESTS_C+=		mbsrtowcs_test
 ATF_TESTS_C+=		mbstowcs_2_test
 ATF_TESTS_C+=		mbtowc_2_test
+ATF_TESTS_C+=		newlocale_cu8_test
 ATF_TESTS_C+=		towctrans_test
 ATF_TESTS_C+=		wcrtomb_test
 ATF_TESTS_C+=		wcsnrtombs_test
diff --git a/lib/libc/tests/locale/newlocale_cu8_test.c b/lib/libc/tests/locale/newlocale_cu8_test.c
new file mode 100644
--- /dev/null
+++ b/lib/libc/tests/locale/newlocale_cu8_test.c
@@ -0,0 +1,73 @@
+#include <sys/param.h>
+
+#include <locale.h>
+
+#include <atf-c.h>
+
+/*
+ * PR269375: Check that creating/using the C.UTF-8 locale does not clobber the
+ * C locale contents.  The issue is cosmetic only as both locales have empty
+ * collate parts, but we need to correctly report the one in use in any case.
+ */
+
+struct {
+	int		lpmask;
+	const char	*lpname;
+} lparts[] = {
+	{ LC_COLLATE_MASK,	"LC_COLLATE" },
+	{ LC_CTYPE_MASK,	"LC_CTYPE" },
+	{ LC_MONETARY_MASK,	"LC_MONETARY" },
+	{ LC_NUMERIC_MASK,	"LC_NUMERIC" },
+	{ LC_TIME_MASK,		"LC_TIME" },
+	{ LC_MESSAGES_MASK,	"LC_MESSAGES" },
+};
+
+void
+check_lparts(const char *step, const char *expected)
+{
+	int i;
+
+	for (i = 0; i < nitems(lparts); i++) {
+		const char *actual;
+
+		actual = querylocale(lparts[i].lpmask, uselocale(NULL));
+		ATF_CHECK_STREQ_MSG(expected, actual, "%s: wrong value for %s",
+		    step, lparts[i].lpname);
+	}
+}
+
+ATF_TC_WITHOUT_HEAD(newlocale_cu8_test);
+ATF_TC_BODY(newlocale_cu8_test, tc)
+{
+	locale_t c, cu8;
+
+	c = newlocale(LC_ALL_MASK, "C", NULL);
+	ATF_REQUIRE(c != NULL);
+
+	ATF_REQUIRE(uselocale(c) != NULL);
+	check_lparts("initial C", "C");
+
+	/*
+	 * Creating the C.UTF-8 locale only after the initial C check is
+	 * deliberate - newlocale() call would clobber the C locale contents,
+	 * hence we want at least the initial check above to be correct.
+	 */
+	cu8 = newlocale(LC_ALL_MASK, "C.UTF-8", NULL);
+	ATF_REQUIRE(cu8 != NULL);
+	ATF_REQUIRE(uselocale(cu8) != NULL);
+	check_lparts("switched to C.UTF-8", "C.UTF-8");
+
+	ATF_REQUIRE(uselocale(c) != NULL);
+	check_lparts("back to C", "C");
+
+	freelocale(c);
+	freelocale(cu8);
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+
+	ATF_TP_ADD_TC(tp, newlocale_cu8_test);
+
+	return (atf_no_error());
+}