diff --git a/history-substring-search.zsh b/history-substring-search.zsh
index c1e51e0..53f707c 100644
--- a/history-substring-search.zsh
+++ b/history-substring-search.zsh
@@ -319,10 +319,28 @@ function _history-substring-search-begin() {
     _history_substring_search_matches_count_sans=$(( _history_substring_search_matches_count - 1 ))
 
     #
-    # initial value of $_history_substring_search_match_index, which
-    # can only be decreased by the history-substring-search-* widgets.
+    # If $_history_substring_search_match_index is equal to
+    # $_history_substring_search_matches_count_plus, this indicates that we
+    # are beyond the beginning of $_history_substring_search_matches.
     #
-    _history_substring_search_match_index=$_history_substring_search_matches_count_plus
+    # If $_history_substring_search_match_index is equal to 0, this indicates
+    # that we are beyond the end of $_history_substring_search_matches.
+    #
+    # If we have initially pressed "up" we have to initialize
+    # $_history_substring_search_match_index to
+    # $_history_substring_search_matches_count_plus so that it will be
+    # decreased to $_history_substring_search_matches_count.
+    #
+    # If we have initially pressed "down" we have to initialize
+    # $_history_substring_search_match_index to
+    # $_history_substring_search_matches_count so that it will be increased to
+    # $_history_substring_search_matches_count_plus.
+    #
+    if [[ $WIDGET == history-substring-search-down ]]; then
+       _history_substring_search_match_index=$_history_substring_search_matches_count
+    else
+      _history_substring_search_match_index=$_history_substring_search_matches_count_plus
+    fi
   fi
 }
 
@@ -465,23 +483,29 @@ function _history-substring-search-up-search() {
   _history_substring_search_move_cursor_eol=true
 
   #
-  # Highlight matches during a history-substring-search:
+  # Highlight matches during history-substring-up-search:
   #
-  # * $_history_substring_search_matches: the current list of matches
-  # * $_history_substring_search_matches_count: the current number of matches
-  # * $_history_substring_search_matches_count_plus: the current number of matches + 1
-  # * $_history_substring_search_matches_count_sans: the current number of matches - 1
-  # * $_history_substring_search_match_index: the number of the current match
+  # The following constants have been initialized in
+  # _history-substring-search-up/down-search():
   #
-  # The range of values that $_history_substring_search_match_index
-  # can take is: [0, $_history_substring_search_matches_count_plus].
-  # A value of 0 indicates that we are beyond the end of
+  # $_history_substring_search_matches is the current list of matches
+  # $_history_substring_search_matches_count is the current number of matches
+  # $_history_substring_search_matches_count_plus is the current number of matches + 1
+  # $_history_substring_search_matches_count_sans is the current number of matches - 1
+  # $_history_substring_search_match_index is the index of the current match
+  #
+  # The range of values that $_history_substring_search_match_index can take
+  # is: [0, $_history_substring_search_matches_count_plus].  A value of 0
+  # indicates that we are beyond the end of
   # $_history_substring_search_matches. A value of
-  # $_history_substring_search_matches_count_plus indicates that we
-  # are beyond the beginning of $_history_substring_search_matches.
+  # $_history_substring_search_matches_count_plus indicates that we are beyond
+  # the beginning of $_history_substring_search_matches.
   #
-  # The initial value of $_history_substring_search_match_index is
-  # $_history_substring_search_matches_count_plus.
+  # In _history-substring-search-up-search() the initial value of
+  # $_history_substring_search_match_index is
+  # $_history_substring_search_matches_count_plus.  This value is set in
+  # _history-substring-search-begin().  _history-substring-search-up-search()
+  # will initially decrease it to $_history_substring_search_matches_count.
   #
   if [[ $_history_substring_search_match_index -ge 2 ]]; then
     #
@@ -538,36 +562,32 @@ function _history-substring-search-down-search() {
   _history_substring_search_move_cursor_eol=true
 
   #
-  # Highlight matches during a history-substring-search:
+  # Highlight matches during history-substring-up-search:
   #
-  # $_history_substring_search_matches: the current list of matches
-  # $_history_substring_search_matches_count: the current number of matches
-  # $_history_substring_search_matches_count_plus: the current number of matches + 1
-  # $_history_substring_search_matches_count_sans: the current number of matches - 1
-  # $_history_substring_search_match_index: the number of the current match
+  # The following constants have been initialized in
+  # _history-substring-search-up/down-search():
   #
-  # The range of values that $_history_substring_search_match_index
-  # can take is: [0, $_history_substring_search_matches_count_plus].
-  # A value of 0 indicates that we are beyond the end of
+  # $_history_substring_search_matches is the current list of matches
+  # $_history_substring_search_matches_count is the current number of matches
+  # $_history_substring_search_matches_count_plus is the current number of matches + 1
+  # $_history_substring_search_matches_count_sans is the current number of matches - 1
+  # $_history_substring_search_match_index is the index of the current match
+  #
+  # The range of values that $_history_substring_search_match_index can take
+  # is: [0, $_history_substring_search_matches_count_plus].  A value of 0
+  # indicates that we are beyond the end of
   # $_history_substring_search_matches. A value of
-  # $_history_substring_search_matches_count_plus indicates that we
-  # are beyond the beginning of $_history_substring_search_matches.
+  # $_history_substring_search_matches_count_plus indicates that we are beyond
+  # the beginning of $_history_substring_search_matches.
   #
-  # The initial value of $_history_substring_search_match_index is
+  # In _history-substring-search-down-search() the initial value of
+  # $_history_substring_search_match_index is
+  # $_history_substring_search_matches_count.  This value is set in
+  # _history-substring-search-begin().
+  # _history-substring-search-down-search() will initially increase it to
   # $_history_substring_search_matches_count_plus.
   #
-  if [[ $_history_substring_search_match_index -eq $_history_substring_search_matches_count_plus ]]; then
-    #
-    # DOWN was pressed immediately. $_history_substring_search_match_index is
-    # still equal to $_history_substring_search_match_number_plus.
-    # However, there is no highlighting yet:
-    #
-    # 1. We have to use $HISTORY_SUBSTRING_SEARCH_HIGHLIGHT_NOT_FOUND
-    #    to highlight the current buffer.
-    #
-    _history_substring_search_query_highlight=$HISTORY_SUBSTRING_SEARCH_HIGHLIGHT_NOT_FOUND
-
-  elif [[ $_history_substring_search_match_index -le $_history_substring_search_matches_count_sans ]]; then
+  if [[ $_history_substring_search_match_index -le $_history_substring_search_matches_count_sans ]]; then
     #
     # Highlight the next match:
     #