diff --git a/src/header/time/mod.rs b/src/header/time/mod.rs
index 2c5a611097..cebe2ac512 100644
--- a/src/header/time/mod.rs
+++ b/src/header/time/mod.rs
@@ -68,14 +68,22 @@ static mut ASCTIME: [c_char; 26] = [0; 26];
 // TODO: timezones
 #[repr(transparent)]
 pub struct TzName {
-    tz: [*const c_char; 2],
+    tz: [*mut c_char; 2],
 }
 
 unsafe impl Sync for TzName {}
 
+static mut TZ_STD: [c_char; 8] = [b'U' as c_char, b'T' as c_char, b'C' as c_char, 0, 0, 0, 0, 0];
+static mut TZ_DST: [c_char; 8] = [b'U' as c_char, b'T' as c_char, b'C' as c_char, 0, 0, 0, 0, 0];
+
 #[allow(non_upper_case_globals)]
 #[no_mangle]
-pub static mut tzname: TzName = TzName { tz: [UTC, UTC] };
+pub static mut tzname: TzName = TzName {
+    tz: [
+        unsafe { TZ_DST.as_mut_ptr() },
+        unsafe { TZ_DST.as_mut_ptr() },
+    ] };
+
 #[allow(non_upper_case_globals)]
 #[no_mangle]
 pub static mut daylight: c_int = 0;
@@ -487,7 +495,7 @@ pub extern "C" fn timer_delete(timerid: timer_t) -> c_int {
 
 #[no_mangle]
 pub extern "C" fn tzset() {
-    // no-op because we only do GMT
+    // no-op because we only do UTC
     // TODO: timezones, parse env var TZ
 }
 
diff --git a/tests/time/tzset.c b/tests/time/tzset.c
index f48c9e050b..87fa15f719 100644
--- a/tests/time/tzset.c
+++ b/tests/time/tzset.c
@@ -5,7 +5,7 @@
 
 extern int daylight;
 extern long timezone;
-extern const char *tzname[2];
+extern char *tzname[2];
 void tzset(void);
 
 int main(void) {