diff --git a/lib/notmuch.h b/lib/notmuch.h
index 86b5b4de..87756838 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -728,13 +728,13 @@ typedef enum {
  * Return the query_string of this query. See notmuch_query_create.
  */
 const char *
-notmuch_query_get_query_string (notmuch_query_t *query);
+notmuch_query_get_query_string (const notmuch_query_t *query);
 
 /**
  * Return the notmuch database of this query. See notmuch_query_create.
  */
 notmuch_database_t *
-notmuch_query_get_database (notmuch_query_t *query);
+notmuch_query_get_database (const notmuch_query_t *query);
 
 /**
  * Exclude values for notmuch_query_set_omit_excluded. The strange
@@ -791,7 +791,7 @@ notmuch_query_set_sort (notmuch_query_t *query, notmuch_sort_t sort);
  * notmuch_query_set_sort.
  */
 notmuch_sort_t
-notmuch_query_get_sort (notmuch_query_t *query);
+notmuch_query_get_sort (const notmuch_query_t *query);
 
 /**
  * Add a tag that will be excluded from the query results by default.
diff --git a/lib/query.cc b/lib/query.cc
index f53215db..8cf0a077 100644
--- a/lib/query.cc
+++ b/lib/query.cc
@@ -98,7 +98,7 @@ notmuch_query_create (notmuch_database_t *notmuch,
 }
 
 const char *
-notmuch_query_get_query_string (notmuch_query_t *query)
+notmuch_query_get_query_string (const notmuch_query_t *query)
 {
     return query->query_string;
 }
@@ -117,7 +117,7 @@ notmuch_query_set_sort (notmuch_query_t *query, notmuch_sort_t sort)
 }
 
 notmuch_sort_t
-notmuch_query_get_sort (notmuch_query_t *query)
+notmuch_query_get_sort (const notmuch_query_t *query)
 {
     return query->sort;
 }
@@ -660,7 +660,7 @@ notmuch_query_count_threads (notmuch_query_t *query)
 }
 
 notmuch_database_t *
-notmuch_query_get_database (notmuch_query_t *query)
+notmuch_query_get_database (const notmuch_query_t *query)
 {
     return query->notmuch;
 }