diff --git a/sql/my_decimal.cc b/sql/my_decimal.cc
index 37d4dd25473b0..be732d4a927d5 100644
--- a/sql/my_decimal.cc
+++ b/sql/my_decimal.cc
@@ -320,7 +320,7 @@ my_decimal *seconds2my_decimal(bool sign,
 }
 
 
-my_decimal *date2my_decimal(MYSQL_TIME *ltime, my_decimal *dec)
+my_decimal *date2my_decimal(const MYSQL_TIME *ltime, my_decimal *dec)
 {
   longlong date= (ltime->year*100L + ltime->month)*100L + ltime->day;
   if (ltime->time_type > MYSQL_TIMESTAMP_DATE)
diff --git a/sql/my_decimal.h b/sql/my_decimal.h
index 78c71d54b6d01..265b370a154c4 100644
--- a/sql/my_decimal.h
+++ b/sql/my_decimal.h
@@ -386,7 +386,7 @@ int string2my_decimal(uint mask, const String *str, my_decimal *d)
 }
 
 
-my_decimal *date2my_decimal(MYSQL_TIME *ltime, my_decimal *dec);
+my_decimal *date2my_decimal(const MYSQL_TIME *ltime, my_decimal *dec);
 
 
 #endif /*defined(MYSQL_SERVER) || defined(EMBEDDED_LIBRARY) */
diff --git a/sql/sql_error.h b/sql/sql_error.h
index 111495fa5667e..e03c3dd4a9382 100644
--- a/sql/sql_error.h
+++ b/sql/sql_error.h
@@ -567,7 +567,7 @@ class ErrConvString : public ErrConv
     : ErrConv(), str(str_arg), len(len_arg), cs(cs_arg) {}
   ErrConvString(const char *str_arg, CHARSET_INFO *cs_arg)
     : ErrConv(), str(str_arg), len(strlen(str_arg)), cs(cs_arg) {}
-  ErrConvString(String *s)
+  ErrConvString(const String *s)
     : ErrConv(), str(s->ptr()), len(s->length()), cs(s->charset()) {}
   const char *ptr() const
   { return err_conv(err_buffer, sizeof(err_buffer), str, len, cs); }