diff --git a/include/rp6502.h b/include/rp6502.h
index 2c0e78b87..434f2d130 100644
--- a/include/rp6502.h
+++ b/include/rp6502.h
@@ -96,11 +96,12 @@ long __fastcall__ ria_call_long (unsigned char op);
 #define RIA_OP_LRAND 0x04
 #define RIA_OP_STDIN_OPT 0x05
 #define RIA_OP_ERRNO_OPT 0x06
+#define RIA_OP_TZSET 0x0D
+#define RIA_OP_TZQUERY 0x0E
 #define RIA_OP_CLOCK 0x0F
 #define RIA_OP_CLOCK_GETRES 0x10
 #define RIA_OP_CLOCK_GETTIME 0x11
 #define RIA_OP_CLOCK_SETTIME 0x12
-#define RIA_OP_CLOCK_GETTIMEZONE 0x13
 #define RIA_OP_OPEN 0x14
 #define RIA_OP_CLOSE 0x15
 #define RIA_OP_READ_XSTACK 0x16
@@ -171,10 +172,6 @@ int __fastcall__ f_setlabel (const char* name);
 int __fastcall__ f_getlabel (const char* path, char* label);
 int __fastcall__ f_getfree (const char* name, unsigned long* free, unsigned long* total);
 
-/* Time zone hack */
-
-void ria_tzset (unsigned long time);
-
 /* XREG location helpers */
 
 #define xreg_ria_keyboard(...) xreg(0, 0, 0, __VA_ARGS__)
diff --git a/include/time.h b/include/time.h
index 5eb6f144a..210e49fb1 100644
--- a/include/time.h
+++ b/include/time.h
@@ -108,6 +108,7 @@ struct tm* __fastcall__ localtime (const time_t* timep);
 time_t __fastcall__ mktime (struct tm* timep);
 size_t __fastcall__ strftime (char* buf, size_t bufsize, const char* format, const struct tm* tm);
 time_t __fastcall__ time (time_t* t);
+void tzset (void);
 
 
 #if __CC65_STD__ >= __CC65_STD_CC65__
@@ -131,9 +132,9 @@ extern struct _timezone {
 #define CLK_TCK                 CLOCKS_PER_SEC
 
 /* POSIX function prototypes */
-int __fastcall__ clock_getres (clockid_t clock_id, struct timespec *res);
-int __fastcall__ clock_gettime (clockid_t clock_id, struct timespec *tp);
-int __fastcall__ clock_settime (clockid_t clock_id, const struct timespec *tp);
+int __fastcall__ clock_getres (clockid_t clock_id, struct timespec* res);
+int __fastcall__ clock_gettime (clockid_t clock_id, struct timespec* tp);
+int __fastcall__ clock_settime (clockid_t clock_id, const struct timespec* tp);
 
 #endif
 
diff --git a/libsrc/rp6502/_localtime.c b/libsrc/rp6502/_localtime.c
new file mode 100644
index 000000000..8c76e3a26
--- /dev/null
+++ b/libsrc/rp6502/_localtime.c
@@ -0,0 +1,31 @@
+#include <rp6502.h>
+#include <time.h>
+#include <stdbool.h>
+
+static bool tzset_set = false;
+
+struct tm* __fastcall__ _time_t_to_tm (const time_t t);
+
+struct tm* __fastcall__ _localtime (const time_t* timep)
+{
+    struct tm* tm;
+    time_t time = *timep;
+    ria_set_axsreg (time);
+    time += ria_call_long (RIA_OP_TZQUERY);
+    tm = _time_t_to_tm (time);
+    tm->tm_isdst = ria_pop_char ();
+    if (!tzset_set) { tzset (); }
+    return tm;
+}
+
+void tzset (void)
+{
+    int ax = ria_call_int (RIA_OP_TZSET);
+    if (ax >= 0) {
+        char i;
+        for (i = 0; i < sizeof (struct _timezone); i++) {
+            ((char*)&_tz)[i] = ria_pop_char ();
+        }
+        tzset_set = true;
+    }
+}
diff --git a/libsrc/rp6502/gettimezone.c b/libsrc/rp6502/gettimezone.c
deleted file mode 100644
index 4c4584c07..000000000
--- a/libsrc/rp6502/gettimezone.c
+++ /dev/null
@@ -1,17 +0,0 @@
-#include <rp6502.h>
-#include <time.h>
-
-int clock_gettimezone (time_t time, clockid_t clock_id, struct _timezone* tz)
-{
-    int ax;
-    ria_set_ax (clock_id);
-    ria_push_long (time);
-    ax = ria_call_int (RIA_OP_CLOCK_GETTIMEZONE);
-    if (ax >= 0) {
-        char i;
-        for (i = 0; i < sizeof (struct _timezone); i++) {
-            ((char*)tz)[i] = ria_pop_char ();
-        }
-    }
-    return ax;
-}
diff --git a/libsrc/rp6502/localtime.s b/libsrc/rp6502/localtime.s
new file mode 100644
index 000000000..89984770d
--- /dev/null
+++ b/libsrc/rp6502/localtime.s
@@ -0,0 +1,12 @@
+;
+; struct tm* __fastcall__ localtime (const time_t* timep);
+;
+
+        .export         _localtime
+
+        .import         __localtime
+
+
+;--------------------------------------------------------------------------
+
+_localtime = __localtime
diff --git a/libsrc/rp6502/ria_tzset.c b/libsrc/rp6502/ria_tzset.c
deleted file mode 100644
index 3f39e44f2..000000000
--- a/libsrc/rp6502/ria_tzset.c
+++ /dev/null
@@ -1,9 +0,0 @@
-#include <rp6502.h>
-#include <time.h>
-
-int clock_gettimezone (time_t time, clockid_t clock_id, struct _timezone* tz);
-
-void ria_tzset (unsigned long time)
-{
-    clock_gettimezone (time, CLOCK_REALTIME, &_tz);
-}