diff --git a/src/wrapper.c b/src/wrapper.c
index 9f727fe..3cf6844 100644
--- a/src/wrapper.c
+++ b/src/wrapper.c
@@ -20,7 +20,7 @@ typedef enum {
   FORMAT_LATEX
 } writer_format;
 
-char* print_document(cmark_node *document, writer_format writer, int options, int width){
+static char* print_document(cmark_node *document, writer_format writer, int options, int width){
   switch (writer) {
   case FORMAT_HTML:
     return cmark_render_html(document, options, NULL);