diff --git a/src/lib/image.h b/src/lib/image.h
index 70ca4b9..045c40b 100644
--- a/src/lib/image.h
+++ b/src/lib/image.h
@@ -100,7 +100,7 @@ ImlibLoader        *__imlib_FindBestLoaderForFile(const char *file,
 ImlibLoader        *__imlib_FindBestLoaderForFormat(const char *format,
                                                     int for_save);
 ImlibLoader        *__imlib_FindBestLoaderForFileFormat(const char *file,
-                                                        char *format,
+                                                        const char *format,
                                                         int for_save);
 void                __imlib_LoaderSetFormats(ImlibLoader * l,
                                              const char *const *fmt,
@@ -155,7 +155,7 @@ void                __imlib_DirtyPixmapsForImage(ImlibImage * im);
 void                __imlib_AttachTag(ImlibImage * im, const char *key,
                                       int val, void *data,
                                       ImlibDataDestructorFunction destructor);
-ImlibImageTag      *__imlib_GetTag(ImlibImage * im, const char *key);
+ImlibImageTag      *__imlib_GetTag(const ImlibImage * im, const char *key);
 ImlibImageTag      *__imlib_RemoveTag(ImlibImage * im, const char *key);
 void                __imlib_FreeTag(ImlibImage * im, ImlibImageTag * t);
 void                __imlib_FreeAllTags(ImlibImage * im);
diff --git a/src/lib/image_tags.c b/src/lib/image_tags.c
index e3c7149..6ffbe75 100644
--- a/src/lib/image_tags.c
+++ b/src/lib/image_tags.c
@@ -34,7 +34,7 @@ __imlib_AttachTag(ImlibImage * im, const char *key, int val, void *data,
 
 /* look up a tage by its key on the image it was attached to */
 __EXPORT__ ImlibImageTag *
-__imlib_GetTag(ImlibImage * im, const char *key)
+__imlib_GetTag(const ImlibImage * im, const char *key)
 {
    ImlibImageTag      *t;
 
diff --git a/src/lib/loaders.c b/src/lib/loaders.c
index 46570aa..56518d5 100644
--- a/src/lib/loaders.c
+++ b/src/lib/loaders.c
@@ -209,7 +209,7 @@ __imlib_FindBestLoaderForFile(const char *file, int for_save)
 }
 
 ImlibLoader        *
-__imlib_FindBestLoaderForFileFormat(const char *file, char *format,
+__imlib_FindBestLoaderForFileFormat(const char *file, const char *format,
                                     int for_save)
 {
    /* if the format is provided ("png" "jpg" etc.) use that */