diff --git a/src/ClockTool.cc b/src/ClockTool.cc
index 893d32be..6192c5ce 100644
--- a/src/ClockTool.cc
+++ b/src/ClockTool.cc
@@ -47,11 +47,13 @@ const char SWITCHES_SECONDS[] = "crsSTX+";
 const char SWITCHES_12_24H[] = "lIrkHT";
 const char SWITCHES_24_12H[] = "kHTlIr";
 const char SWITCH_AM_PM[] = "pP";
+const char IGNORE_AFTER_TRIGGER[] = "0123456789";
 
 int showSeconds(const std::string& fmt) {
 
     return FbTk::StringUtil::findCharFromAlphabetAfterTrigger(
-                    fmt, '%', SWITCHES_SECONDS, sizeof(SWITCHES_SECONDS), 0) != std::string::npos;
+        fmt, '%', SWITCHES_SECONDS, sizeof(SWITCHES_SECONDS), 0,
+        IGNORE_AFTER_TRIGGER, sizeof(IGNORE_AFTER_TRIGGER)) != std::string::npos;
 }
 
 uint64_t calcNextTimeout(const std::string& fmt) {
@@ -82,7 +84,8 @@ public:
         // does the current format string contain something with 24/12h?
         size_t found;
         size_t pos = FbTk::StringUtil::findCharFromAlphabetAfterTrigger(
-                m_tool.timeFormat(), '%', SWITCHES_24_12H, sizeof(SWITCHES_24_12H), &found);
+            m_tool.timeFormat(), '%', SWITCHES_24_12H, sizeof(SWITCHES_24_12H), &found,
+            IGNORE_AFTER_TRIGGER, sizeof(IGNORE_AFTER_TRIGGER));
 
         if (pos != std::string::npos) { // if so, exchange it with 12/24h
             std::string newformat = m_tool.timeFormat();
@@ -90,7 +93,8 @@ public:
 
             if (found < 3) { // 24h? erase %P/%p (AM|PM / am|pm)
                 pos = FbTk::StringUtil::findCharFromAlphabetAfterTrigger(
-                    newformat, '%', SWITCH_AM_PM, sizeof(SWITCH_AM_PM), 0);
+                    newformat, '%', SWITCH_AM_PM, sizeof(SWITCH_AM_PM), 0,
+                    IGNORE_AFTER_TRIGGER, sizeof(IGNORE_AFTER_TRIGGER));
                 if (pos != std::string::npos) {
                     newformat.erase(pos, 2);
                 }
@@ -107,7 +111,8 @@ private:
     void setClockModeLabel() {
         _FB_USES_NLS;
         if (FbTk::StringUtil::findCharFromAlphabetAfterTrigger(
-            m_tool.timeFormat(), '%', SWITCHES_24_12H, 3, 0) != std::string::npos) {
+            m_tool.timeFormat(), '%', SWITCHES_24_12H, 3, 0,
+            IGNORE_AFTER_TRIGGER, sizeof(IGNORE_AFTER_TRIGGER)) != std::string::npos) {
             setLabel( _FB_XTEXT(Toolbar, Clock24,   "Clock: 24h",   "set Clockmode to 24h") );
         } else {
             setLabel( _FB_XTEXT(Toolbar, Clock12,   "Clock: 12h",   "set Clockmode to 12h") );
diff --git a/src/FbTk/StringUtil.cc b/src/FbTk/StringUtil.cc
index 63da3837..b5f373f7 100644
--- a/src/FbTk/StringUtil.cc
+++ b/src/FbTk/StringUtil.cc
@@ -274,9 +274,16 @@ string findExtension(const string &filename) {
     return filename.substr(start_pos + 1);
 }
 
-string::size_type findCharFromAlphabetAfterTrigger(const std::string& in, char trigger, const char alphabet[], size_t len_alphabet, size_t* found) {
+    string::size_type findCharFromAlphabetAfterTrigger(const std::string& in, char trigger, const char alphabet[], size_t len_alphabet, size_t* found, const char ignore_after_trigger[], size_t len_ignore_after_trigger) {
     for (const char* s = in.c_str(); *s != '\0'; ) {
         if (*s++ == trigger && *s != '\0') {
+            auto end = ignore_after_trigger + len_ignore_after_trigger;
+            while (std::find(ignore_after_trigger, end, *s) != end)
+                s++;
+
+            if (*s == '\0')
+                return string::npos;
+
             for (const char* a = alphabet; (a - alphabet) < static_cast<ssize_t>(len_alphabet); ++a) {
                 if (*s == *a) {
                     if (found) {
diff --git a/src/FbTk/StringUtil.hh b/src/FbTk/StringUtil.hh
index bfa3a5cd..5e0d0d48 100644
--- a/src/FbTk/StringUtil.hh
+++ b/src/FbTk/StringUtil.hh
@@ -69,7 +69,7 @@ std::string findExtension(const std::string &filename);
 /// @return std::string::npos if nothing found
 std::string::size_type findCharFromAlphabetAfterTrigger(const std::string& in,
     char trigger,
-    const char alphabet[], size_t len_alphabet, size_t* found);
+    const char alphabet[], size_t len_alphabet, size_t* found, const char ignore_after_trigger[] = "", size_t len_ignore_after_trigger = 0);
 
 /// @return copy of original with find_string replaced with "replace"
 std::string replaceString(const std::string &original,