diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index 70d90d4..b5faf13 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -4336,7 +4336,10 @@
 formatfloat(char *buf, size_t buflen, int flags,
             int prec, int type, PyObject *v)
 {
+	char *tmp;
 	double x;
+	Py_ssize_t len;
+
 	x = PyFloat_AsDouble(v);
 	if (x == -1.0 && PyErr_Occurred()) {
 		PyErr_Format(PyExc_TypeError, "float argument required, "
@@ -4381,9 +4384,20 @@
 			"formatted float is too long (precision too large?)");
 		return -1;
 	}
-	_PyOS_double_to_string(buf, buflen, x, type, prec,
-                            (flags&F_ALT)?Py_DTSF_ALT:0, NULL);
-	return (int)strlen(buf);
+	tmp = PyOS_double_to_string(x, type, prec,
+				    (flags&F_ALT)?Py_DTSF_ALT:0, NULL);
+	if (!tmp)
+		return -1;
+	len = strlen(tmp);
+	if (len >= buflen) {
+		PyErr_SetString(PyExc_OverflowError,
+			"formatted float is too long (precision too large?)");
+		PyMem_Free(tmp);
+		return -1;
+	}
+	strcpy(buf, tmp);
+	PyMem_Free(tmp);
+	return (int)len;
 }
 
 /* _PyString_FormatLong emulates the format codes d, u, o, x and X, and
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 6eac358..65c10b1 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -8289,18 +8289,6 @@
 }
 
 static int
-doubletounicode(Py_UNICODE *buffer, size_t len, int format_code,
-                int precision, int flags, double x)
-{
-    Py_ssize_t result;
-
-    _PyOS_double_to_string((char *)buffer, len, x, format_code, precision,
-                           flags, NULL);
-    result = strtounicode(buffer, (char *)buffer);
-    return Py_SAFE_DOWNCAST(result, Py_ssize_t, int);
-}
-
-static int
 longtounicode(Py_UNICODE *buffer, size_t len, const char *format, long x)
 {
     Py_ssize_t result;
@@ -8323,6 +8311,8 @@
             PyObject *v)
 {
     double x;
+    Py_ssize_t result;
+    char *tmp;
 
     x = PyFloat_AsDouble(v);
     if (x == -1.0 && PyErr_Occurred())
@@ -8365,8 +8355,15 @@
                         "formatted float is too long (precision too large?)");
         return -1;
     }
-    return doubletounicode(buf, buflen, type, prec,
-                           (flags&F_ALT)?Py_DTSF_ALT:0, x);
+
+    tmp = PyOS_double_to_string(x, type, prec,
+                                (flags&F_ALT)?Py_DTSF_ALT:0, NULL);
+    if (!tmp)
+        return -1;
+
+    result = strtounicode(buf, tmp);
+    PyMem_Free(tmp);
+    return Py_SAFE_DOWNCAST(result, Py_ssize_t, int);
 }
 
 static PyObject*