1 files changed, 2 insertions, 2 deletions
diff --git a/src/df.c b/src/df.c
index 1b27675bf..982d60742 100644
--- a/src/df.c
+++ b/src/df.c
@@ -321,7 +321,7 @@ get_header (void)
 
 /* Is FSTYPE a type of file system that should be listed?  */
 
-static bool
+static bool _GL_ATTRIBUTE_PURE
 selected_fstype (const char *fstype)
 {
   const struct fs_type_list *fsp;
@@ -336,7 +336,7 @@ selected_fstype (const char *fstype)
 
 /* Is FSTYPE a type of file system that should be omitted?  */
 
-static bool
+static bool _GL_ATTRIBUTE_PURE
 excluded_fstype (const char *fstype)
 {
   const struct fs_type_list *fsp;