diff --git a/src/history_file.cpp b/src/history_file.cpp
index b1e00b6f7..c21adc490 100644
--- a/src/history_file.cpp
+++ b/src/history_file.cpp
@@ -68,13 +68,14 @@ static void replace_all(std::string *str, const char *needle, const char *replac
     }
 }
 
-void escape_yaml_fish_2_0(std::string *str) {
+// Support for escaping and unescaping the nonstandard "yaml" format introduced in fish 2.0.
+static void escape_yaml_fish_2_0(std::string *str) {
     replace_all(str, "\\", "\\\\");  // replace one backslash with two
     replace_all(str, "\n", "\\n");   // replace newline with backslash + literal n
 }
 
 /// This function is called frequently, so it ought to be fast.
-void unescape_yaml_fish_2_0(std::string *str) {
+static void unescape_yaml_fish_2_0(std::string *str) {
     size_t cursor = 0, size = str->size();
     while (cursor < size) {
         // Operate on a const version of str, to avoid needless COWs that at() does.
diff --git a/src/history_file.h b/src/history_file.h
index bc0065099..a86fecf97 100644
--- a/src/history_file.h
+++ b/src/history_file.h
@@ -70,8 +70,4 @@ class history_file_contents_t {
 /// Append a history item to a buffer, in preparation for outputting it to the history file.
 void append_history_item_to_buffer(const history_item_t &item, std::string *buffer);
 
-// Support for escaping and unescaping the nonstandard "yaml" format introduced in fish 2.0.
-void escape_yaml_fish_2_0(std::string *str);
-void unescape_yaml_fish_2_0(std::string *str);
-
 #endif