diff --git a/Modules/_elementtree.c b/Modules/_elementtree.c
index 5983a3b..6373c48 100644
--- a/Modules/_elementtree.c
+++ b/Modules/_elementtree.c
@@ -2138,13 +2138,15 @@
 static void
 expat_set_error(const char* message, int line, int column)
 {
-    PyObject *error;
-    PyObject *position;
-    char buffer[256];
+    PyObject *errmsg, *error, *position;
 
-    sprintf(buffer, "%.100s: line %d, column %d", message, line, column);
+    errmsg = PyUnicode_FromFormat("%s: line %d, column %d",
+                                  message, line, column);
+    if (errmsg == NULL)
+        return;
 
-    error = PyObject_CallFunction(elementtree_parseerror_obj, "s", buffer);
+    error = PyObject_CallFunction(elementtree_parseerror_obj, "O", errmsg);
+    Py_DECREF(errmsg);
     if (!error)
         return;
 
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index f19d0df..75dbe57 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -43,11 +43,9 @@
 sizeof_error(const char* fatname, const char* typname,
     int expected, int got)
 {
-    char buf[1024];
-    PyOS_snprintf(buf, sizeof(buf),
-        "%.200s #define == %d but sizeof(%.200s) == %d",
+    PyErr_Format(TestError,
+        "%s #define == %d but sizeof(%s) == %d",
         fatname, expected, typname, got);
-    PyErr_SetString(TestError, buf);
     return (PyObject*)NULL;
 }
 
diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index 10a4ed7..b05675c 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -680,8 +680,8 @@
 static void
 debug_cycle(char *msg, PyObject *op)
 {
-    PySys_WriteStderr("gc: %.100s <%.100s %p>\n",
-                      msg, Py_TYPE(op)->tp_name, op);
+    PySys_FormatStderr("gc: %s <%s %p>\n",
+                       msg, Py_TYPE(op)->tp_name, op);
 }
 
 /* Handle uncollectable garbage (cycles with finalizers, and stuff reachable
diff --git a/Modules/pyexpat.c b/Modules/pyexpat.c
index ee59baf..9b78d7e 100644
--- a/Modules/pyexpat.c
+++ b/Modules/pyexpat.c
@@ -100,16 +100,17 @@
 set_error(xmlparseobject *self, enum XML_Error code)
 {
     PyObject *err;
-    char buffer[256];
+    PyObject *buffer;
     XML_Parser parser = self->itself;
     int lineno = XML_GetErrorLineNumber(parser);
     int column = XML_GetErrorColumnNumber(parser);
 
-    /* There is no risk of overflowing this buffer, since
-       even for 64-bit integers, there is sufficient space. */
-    sprintf(buffer, "%.200s: line %i, column %i",
-            XML_ErrorString(code), lineno, column);
-    err = PyObject_CallFunction(ErrorObject, "s", buffer);
+    buffer = PyUnicode_FromFormat("%s: line %i, column %i",
+                                  XML_ErrorString(code), lineno, column);
+    if (buffer == NULL)
+        return NULL;
+    err = PyObject_CallFunction(ErrorObject, "O", buffer);
+    Py_DECREF(buffer);
     if (  err != NULL
           && set_error_attr(err, "code", code)
           && set_error_attr(err, "offset", column)
diff --git a/Modules/timemodule.c b/Modules/timemodule.c
index c3b51ef..b24cc35 100644
--- a/Modules/timemodule.c
+++ b/Modules/timemodule.c
@@ -601,31 +601,20 @@
 {
     /* Inspired by Open Group reference implementation available at
      * http://pubs.opengroup.org/onlinepubs/009695399/functions/asctime.html */
-    static char wday_name[7][3] = {
+    static char wday_name[7][4] = {
         "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
     };
-    static char mon_name[12][3] = {
+    static char mon_name[12][4] = {
         "Jan", "Feb", "Mar", "Apr", "May", "Jun",
         "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
     };
-    char buf[20]; /* 'Sun Sep 16 01:03:52\0' */
-    int n;
-
-    n = PyOS_snprintf(buf, sizeof(buf), "%.3s %.3s%3d %.2d:%.2d:%.2d",
-                      wday_name[timeptr->tm_wday],
-                      mon_name[timeptr->tm_mon],
-                      timeptr->tm_mday, timeptr->tm_hour,
-                      timeptr->tm_min, timeptr->tm_sec);
-    /* XXX: since the fields used by snprintf above are validated in checktm,
-     * the following condition should never trigger. We keep the check because
-     * historically fixed size buffer used in asctime was the source of
-     * crashes. */
-    if (n + 1 != sizeof(buf)) {
-        PyErr_SetString(PyExc_ValueError, "unconvertible time");
-        return NULL;
-    }
-
-    return PyUnicode_FromFormat("%s %d", buf, 1900 + timeptr->tm_year);
+    return PyUnicode_FromFormat(
+        "%s %s%3d %.2d:%.2d:%.2d %d",
+        wday_name[timeptr->tm_wday],
+        mon_name[timeptr->tm_mon],
+        timeptr->tm_mday, timeptr->tm_hour,
+        timeptr->tm_min, timeptr->tm_sec,
+        1900 + timeptr->tm_year);
 }
 
 static PyObject *