Implement PEP 393.
diff --git a/Objects/stringlib/find.h b/Objects/stringlib/find.h
index ce615dc..7cce156 100644
--- a/Objects/stringlib/find.h
+++ b/Objects/stringlib/find.h
@@ -1,14 +1,11 @@
 /* stringlib: find/index implementation */
 
-#ifndef STRINGLIB_FIND_H
-#define STRINGLIB_FIND_H
-
 #ifndef STRINGLIB_FASTSEARCH_H
 #error must include "stringlib/fastsearch.h" before including this module
 #endif
 
 Py_LOCAL_INLINE(Py_ssize_t)
-stringlib_find(const STRINGLIB_CHAR* str, Py_ssize_t str_len,
+STRINGLIB(find)(const STRINGLIB_CHAR* str, Py_ssize_t str_len,
                const STRINGLIB_CHAR* sub, Py_ssize_t sub_len,
                Py_ssize_t offset)
 {
@@ -19,7 +16,7 @@
     if (sub_len == 0)
         return offset;
 
-    pos = fastsearch(str, str_len, sub, sub_len, -1, FAST_SEARCH);
+    pos = FASTSEARCH(str, str_len, sub, sub_len, -1, FAST_SEARCH);
 
     if (pos >= 0)
         pos += offset;
@@ -28,7 +25,7 @@
 }
 
 Py_LOCAL_INLINE(Py_ssize_t)
-stringlib_rfind(const STRINGLIB_CHAR* str, Py_ssize_t str_len,
+STRINGLIB(rfind)(const STRINGLIB_CHAR* str, Py_ssize_t str_len,
                 const STRINGLIB_CHAR* sub, Py_ssize_t sub_len,
                 Py_ssize_t offset)
 {
@@ -39,7 +36,7 @@
     if (sub_len == 0)
         return str_len + offset;
 
-    pos = fastsearch(str, str_len, sub, sub_len, -1, FAST_RSEARCH);
+    pos = FASTSEARCH(str, str_len, sub, sub_len, -1, FAST_RSEARCH);
 
     if (pos >= 0)
         pos += offset;
@@ -63,29 +60,29 @@
     }
 
 Py_LOCAL_INLINE(Py_ssize_t)
-stringlib_find_slice(const STRINGLIB_CHAR* str, Py_ssize_t str_len,
+STRINGLIB(find_slice)(const STRINGLIB_CHAR* str, Py_ssize_t str_len,
                      const STRINGLIB_CHAR* sub, Py_ssize_t sub_len,
                      Py_ssize_t start, Py_ssize_t end)
 {
     ADJUST_INDICES(start, end, str_len);
-    return stringlib_find(str + start, end - start, sub, sub_len, start);
+    return STRINGLIB(find)(str + start, end - start, sub, sub_len, start);
 }
 
 Py_LOCAL_INLINE(Py_ssize_t)
-stringlib_rfind_slice(const STRINGLIB_CHAR* str, Py_ssize_t str_len,
+STRINGLIB(rfind_slice)(const STRINGLIB_CHAR* str, Py_ssize_t str_len,
                       const STRINGLIB_CHAR* sub, Py_ssize_t sub_len,
                       Py_ssize_t start, Py_ssize_t end)
 {
     ADJUST_INDICES(start, end, str_len);
-    return stringlib_rfind(str + start, end - start, sub, sub_len, start);
+    return STRINGLIB(rfind)(str + start, end - start, sub, sub_len, start);
 }
 
 #ifdef STRINGLIB_WANT_CONTAINS_OBJ
 
 Py_LOCAL_INLINE(int)
-stringlib_contains_obj(PyObject* str, PyObject* sub)
+STRINGLIB(contains_obj)(PyObject* str, PyObject* sub)
 {
-    return stringlib_find(
+    return STRINGLIB(find)(
         STRINGLIB_STR(str), STRINGLIB_LEN(str),
         STRINGLIB_STR(sub), STRINGLIB_LEN(sub), 0
         ) != -1;
@@ -105,7 +102,7 @@
 #define FORMAT_BUFFER_SIZE 50
 
 Py_LOCAL_INLINE(int)
-stringlib_parse_args_finds(const char * function_name, PyObject *args,
+STRINGLIB(parse_args_finds)(const char * function_name, PyObject *args,
                            PyObject **subobj,
                            Py_ssize_t *start, Py_ssize_t *end)
 {
@@ -153,13 +150,13 @@
 */
 
 Py_LOCAL_INLINE(int)
-stringlib_parse_args_finds_unicode(const char * function_name, PyObject *args,
+STRINGLIB(parse_args_finds_unicode)(const char * function_name, PyObject *args,
                                    PyUnicodeObject **substring,
                                    Py_ssize_t *start, Py_ssize_t *end)
 {
     PyObject *tmp_substring;
 
-    if(stringlib_parse_args_finds(function_name, args, &tmp_substring,
+    if(STRINGLIB(parse_args_finds)(function_name, args, &tmp_substring,
                                   start, end)) {
         tmp_substring = PyUnicode_FromObject(tmp_substring);
         if (!tmp_substring)
@@ -171,5 +168,3 @@
 }
 
 #endif /* STRINGLIB_IS_UNICODE */
-
-#endif /* STRINGLIB_FIND_H */