--- a/src/lib/strfuncs.c	Tue May 02 18:40:43 2017 +0300
+++ b/src/lib/strfuncs.c	Tue May 02 15:38:00 2017 +0300
@@ -733,12 +733,14 @@
 
 const char *dec2str(uintmax_t number)
 {
-	char *buffer;
+	return dec2str_buf(t_malloc_no0(MAX_INT_STRLEN), number);
+}
+
+char *dec2str_buf(char buffer[STATIC_ARRAY MAX_INT_STRLEN], uintmax_t number)
+{
 	int pos;
 
 	pos = MAX_INT_STRLEN;
-	buffer = t_malloc(pos);
-
 	buffer[--pos] = '\0';
 	do {
 		buffer[--pos] = (number % 10) + '0';

--- a/src/lib/strfuncs.h	Tue May 02 18:40:43 2017 +0300
+++ b/src/lib/strfuncs.h	Tue May 02 15:38:00 2017 +0300
@@ -94,6 +94,10 @@
 const char **t_strsplit_tab(const char *data) ATTR_MALLOC ATTR_RETURNS_NONNULL;
 
 const char *dec2str(uintmax_t number);
+/* Use the given buffer to write out the number. Returns pointer to the
+   written number in the buffer. Note that this isn't the same as the beginning
+   of the buffer. */
+char *dec2str_buf(char buffer[STATIC_ARRAY MAX_INT_STRLEN], uintmax_t number);
 
 /* Return length of NULL-terminated list string array */
 unsigned int str_array_length(const char *const *arr) ATTR_PURE;