diff --git a/lib/cppmyth/CMakeLists.txt b/lib/cppmyth/CMakeLists.txt
index 9e3a5bd8..d09006bd 100644
--- a/lib/cppmyth/CMakeLists.txt
+++ b/lib/cppmyth/CMakeLists.txt
@@ -15,7 +15,7 @@ endif ()
 # set lib version here
 set (PACKAGE_VERSION_MAJOR 2)
 set (PACKAGE_VERSION_MINOR 17)
-set (PACKAGE_VERSION_PATCH 3)
+set (PACKAGE_VERSION_PATCH 4)
 
 set (PACKAGE_VERSION ${PACKAGE_VERSION_MAJOR}.${PACKAGE_VERSION_MINOR}.${PACKAGE_VERSION_PATCH})
 set (PACKAGE_LIB_SOVERSION ${PACKAGE_VERSION_MAJOR})
diff --git a/lib/cppmyth/src/private/builtin.c b/lib/cppmyth/src/private/builtin.c
index 55f77e4d..86a3ed27 100644
--- a/lib/cppmyth/src/private/builtin.c
+++ b/lib/cppmyth/src/private/builtin.c
@@ -1,5 +1,5 @@
 /*
- *      Copyright (C) 2014-2023 Jean-Luc Barriere
+ *      Copyright (C) 2014-2024 Jean-Luc Barriere
  *
  *  This Program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -215,6 +215,42 @@ int hex_to_num(const char *str, int *num)
   return 0;
 }
 
+unsigned uint_to_strdec(unsigned u, char *str, unsigned len, int pad)
+{
+  static const char g[10] = {
+    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
+  };
+  if (len)
+  {
+    char *ptr = str, *end = str + len;
+    unsigned n = u, n10 = u / 10;
+    do
+    {
+      *ptr++ = g[n - n10 * 10];
+      n = n10;
+    } while ((n10 = n / 10) > 0 && ptr < end);
+    if (ptr < end)
+    {
+      /* push last digit */
+      if (n > 0)
+        *ptr++ = g[n];
+      /* padding */
+      if (pad)
+        while (ptr < end) *ptr++ = '0';
+    }
+    len = ptr - str;
+    /* reorder digits */
+    while (--ptr > str)
+    {
+      char c = *str;
+      *str = *ptr;
+      *ptr = c;
+      ++str;
+    }
+  }
+  return len;
+}
+
 time_t __timegm(struct tm *utctime_tm)
 {
   time_t time;
@@ -384,13 +420,20 @@ void time_to_iso8601utc(time_t time, BUILTIN_BUFFER *str)
     str->data[0] = '\0';
     return;
   }
-  snprintf(str->data, sizeof(BUILTIN_BUFFER), "%4.4d-%2.2d-%2.2dT%2.2d:%2.2d:%2.2dZ",
-          time_tm.tm_year + 1900,
-          time_tm.tm_mon + 1,
-          time_tm.tm_mday,
-          time_tm.tm_hour,
-          time_tm.tm_min,
-          time_tm.tm_sec);
+  /* yyyy-MM-ddTHH:mm:ssZ */
+  uint_to_strdec(time_tm.tm_year + 1900, str->data, 4, 1);
+  str->data[4] = '-';
+  uint_to_strdec(time_tm.tm_mon + 1, str->data + 5, 2, 1);
+  str->data[7] = '-';
+  uint_to_strdec(time_tm.tm_mday, str->data + 8, 2, 1);
+  str->data[10] = 'T';
+  uint_to_strdec(time_tm.tm_hour, str->data + 11, 2, 1);
+  str->data[13] = ':';
+  uint_to_strdec(time_tm.tm_min, str->data + 14, 2, 1);
+  str->data[16] = ':';
+  uint_to_strdec(time_tm.tm_sec, str->data + 17, 2, 1);
+  str->data[19] = 'Z';
+  str->data[20] = '\0';
 }
 
 void time_to_iso8601(time_t time, BUILTIN_BUFFER *str)
@@ -402,13 +445,19 @@ void time_to_iso8601(time_t time, BUILTIN_BUFFER *str)
     str->data[0] = '\0';
     return;
   }
-  snprintf(str->data, sizeof(BUILTIN_BUFFER), "%4.4d-%2.2d-%2.2dT%2.2d:%2.2d:%2.2d",
-          time_tm.tm_year + 1900,
-          time_tm.tm_mon + 1,
-          time_tm.tm_mday,
-          time_tm.tm_hour,
-          time_tm.tm_min,
-          time_tm.tm_sec);
+  /* yyyy-MM-ddTHH:mm:ss */
+  uint_to_strdec(time_tm.tm_year + 1900, str->data, 4, 1);
+  str->data[4] = '-';
+  uint_to_strdec(time_tm.tm_mon + 1, str->data + 5, 2, 1);
+  str->data[7] = '-';
+  uint_to_strdec(time_tm.tm_mday, str->data + 8, 2, 1);
+  str->data[10] = 'T';
+  uint_to_strdec(time_tm.tm_hour, str->data + 11, 2, 1);
+  str->data[13] = ':';
+  uint_to_strdec(time_tm.tm_min, str->data + 14, 2, 1);
+  str->data[16] = ':';
+  uint_to_strdec(time_tm.tm_sec, str->data + 17, 2, 1);
+  str->data[19] = '\0';
 }
 
 void time_to_isodate(time_t time, BUILTIN_BUFFER *str)
@@ -420,10 +469,12 @@ void time_to_isodate(time_t time, BUILTIN_BUFFER *str)
     str->data[0] = '\0';
     return;
   }
-  snprintf(str->data, sizeof(BUILTIN_BUFFER), "%4.4d-%2.2d-%2.2d",
-          time_tm.tm_year + 1900,
-          time_tm.tm_mon + 1,
-          time_tm.tm_mday);
+  uint_to_strdec(time_tm.tm_year + 1900, str->data, 4, 1);
+  str->data[4] = '-';
+  uint_to_strdec(time_tm.tm_mon + 1, str->data + 5, 2, 1);
+  str->data[7] = '-';
+  uint_to_strdec(time_tm.tm_mday, str->data + 8, 2, 1);
+  str->data[10] = '\0';
 }
 
 tz_t *time_tz(time_t time, tz_t* tz) {
diff --git a/lib/cppmyth/src/private/builtin.h b/lib/cppmyth/src/private/builtin.h
index 6286451b..846ded05 100644
--- a/lib/cppmyth/src/private/builtin.h
+++ b/lib/cppmyth/src/private/builtin.h
@@ -100,22 +100,28 @@ static CC_INLINE void int8_to_string(int8_t num, BUILTIN_BUFFER *str)
   snprintf(str->data, sizeof(BUILTIN_BUFFER), "%d", num);
 }
 
+#define uint_to_strdec __uintstrdec
+extern unsigned uint_to_strdec(unsigned u, char *str, unsigned len, int pad);
+
 #define uint32_to_string __uint32str
 static CC_INLINE void uint32_to_string(uint32_t num, BUILTIN_BUFFER *str)
 {
-  snprintf(str->data, sizeof(BUILTIN_BUFFER), "%lu", (unsigned long)num);
+  unsigned len = uint_to_strdec(num, str->data, 10, 0);
+  str->data[len] = '\0';
 }
 
 #define uint16_to_string __uint16str
 static CC_INLINE void uint16_to_string(uint16_t num, BUILTIN_BUFFER *str)
 {
-  snprintf(str->data, sizeof(BUILTIN_BUFFER), "%u", num);
+  unsigned len = uint_to_strdec(num, str->data, 5, 0);
+  str->data[len] = '\0';
 }
 
 #define uint8_to_string __uint8str
 static CC_INLINE void uint8_to_string(uint8_t num, BUILTIN_BUFFER *str)
 {
-  snprintf(str->data, sizeof(BUILTIN_BUFFER), "%u", num);
+  unsigned len = uint_to_strdec(num, str->data, 3, 0);
+  str->data[len] = '\0';
 }
 
 #define double_to_string __doublestr