diff --git a/src/buffer.c b/src/buffer.c
index cf19f0274..f3159948c 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -195,7 +195,7 @@ void cmark_strbuf_normalize_whitespace(cmark_strbuf *s) {
 }
 
 // Destructively unescape a string: remove backslashes before punctuation chars.
-extern void cmark_strbuf_unescape(cmark_strbuf *buf) {
+void cmark_strbuf_unescape(cmark_strbuf *buf) {
   bufsize_t r, w;
 
   for (r = 0, w = 0; r < buf->size; ++r) {
diff --git a/src/houdini.h b/src/houdini.h
index d523eb355..cc688adfb 100644
--- a/src/houdini.h
+++ b/src/houdini.h
@@ -23,16 +23,16 @@ extern "C" {
 #define HOUDINI_ESCAPED_SIZE(x) (((x)*12) / 10)
 #define HOUDINI_UNESCAPED_SIZE(x) (x)
 
-extern bufsize_t houdini_unescape_ent(cmark_strbuf *ob, const uint8_t *src,
-                                      bufsize_t size);
-extern int houdini_escape_html0(cmark_strbuf *ob, const uint8_t *src,
-                                bufsize_t size, int secure);
-extern int houdini_unescape_html(cmark_strbuf *ob, const uint8_t *src,
-                                 bufsize_t size);
-extern void houdini_unescape_html_f(cmark_strbuf *ob, const uint8_t *src,
-                                    bufsize_t size);
-extern int houdini_escape_href(cmark_strbuf *ob, const uint8_t *src,
+bufsize_t houdini_unescape_ent(cmark_strbuf *ob, const uint8_t *src,
                                bufsize_t size);
+int houdini_escape_html0(cmark_strbuf *ob, const uint8_t *src,
+                         bufsize_t size, int secure);
+int houdini_unescape_html(cmark_strbuf *ob, const uint8_t *src,
+                          bufsize_t size);
+void houdini_unescape_html_f(cmark_strbuf *ob, const uint8_t *src,
+                             bufsize_t size);
+int houdini_escape_href(cmark_strbuf *ob, const uint8_t *src,
+                        bufsize_t size);
 
 #ifdef __cplusplus
 }
diff --git a/src/references.h b/src/references.h
index b069d920c..27f15de2a 100644
--- a/src/references.h
+++ b/src/references.h
@@ -33,8 +33,8 @@ cmark_reference_map *cmark_reference_map_new(cmark_mem *mem);
 void cmark_reference_map_free(cmark_reference_map *map);
 cmark_reference *cmark_reference_lookup(cmark_reference_map *map,
                                         cmark_chunk *label);
-extern void cmark_reference_create(cmark_reference_map *map, cmark_chunk *label,
-                                   cmark_chunk *url, cmark_chunk *title);
+void cmark_reference_create(cmark_reference_map *map, cmark_chunk *label,
+                            cmark_chunk *url, cmark_chunk *title);
 
 #ifdef __cplusplus
 }