diff --git a/chprintf.c b/chprintf.c
index aa59370..a149a86 100644
--- a/chprintf.c
+++ b/chprintf.c
@@ -82,7 +82,7 @@ static char *long_to_string_with_divisor(char *p,
 
 // default prescision = 13
 // g.mmm kkk hhh
-#define MAX_FREQ_PRESCISION 13
+#define MAX_FREQ_PRESCISION 15
 #define FREQ_PSET           1
 #define FREQ_NO_SPACE       2
 #define FREQ_PREFIX_SPACE   4
diff --git a/sa_core.c b/sa_core.c
index 4822ba5..949bcd2 100644
--- a/sa_core.c
+++ b/sa_core.c
@@ -136,7 +136,7 @@ void update_min_max_freq(void)
     minFreq = 0;
 #ifdef TINYSA4
     if (ultra)
-      maxFreq = 9900000000.0; // ULTRA_MAX_FREQ;  // make use of harmonic mode above ULTRA_MAX_FREQ
+      maxFreq = 12000000000; // ULTRA_MAX_FREQ;  // make use of harmonic mode above ULTRA_MAX_FREQ
     else
       maxFreq =  LOW_MAX_FREQ;
 #else