diff --git a/src/alsa.c b/src/alsa.c
index 2907813..3947fa7 100644
--- a/src/alsa.c
+++ b/src/alsa.c
@@ -45,7 +45,7 @@ void fatal_alsa_error(const char *msg, int err) {
 //
 
 // return the element with the exact matching name
-struct alsa_elem *get_elem_by_name(GArray *elems, char *name) {
+struct alsa_elem *get_elem_by_name(GArray *elems, const char *name) {
   for (int i = 0; i < elems->len; i++) {
     struct alsa_elem *elem = &g_array_index(elems, struct alsa_elem, i);
 
@@ -60,7 +60,7 @@ struct alsa_elem *get_elem_by_name(GArray *elems, char *name) {
 }
 
 // return the first element with a name starting with the given prefix
-struct alsa_elem *get_elem_by_prefix(GArray *elems, char *prefix) {
+struct alsa_elem *get_elem_by_prefix(GArray *elems, const char *prefix) {
   int prefix_len = strlen(prefix);
 
   for (int i = 0; i < elems->len; i++) {
@@ -81,7 +81,11 @@ struct alsa_elem *get_elem_by_prefix(GArray *elems, char *prefix) {
 // e.g. get_max_elem_by_name(elems, "Line", "Pad Capture Switch")
 // will return 8 when the last pad capture switch is
 // "Line In 8 Pad Capture Switch"
-int get_max_elem_by_name(GArray *elems, char *prefix, char *needle) {
+int get_max_elem_by_name(
+  GArray *elems,
+  const char *prefix,
+  const char *needle
+) {
   int max = 0;
   int l = strlen(prefix);
 
diff --git a/src/alsa.h b/src/alsa.h
index 6cbaaf8..64b5cc1 100644
--- a/src/alsa.h
+++ b/src/alsa.h
@@ -198,9 +198,13 @@ struct alsa_card {
 void fatal_alsa_error(const char *msg, int err);
 
 // locate elements or get information about them
-struct alsa_elem *get_elem_by_name(GArray *elems, char *name);
-struct alsa_elem *get_elem_by_prefix(GArray *elems, char *prefix);
-int get_max_elem_by_name(GArray *elems, char *prefix, char *needle);
+struct alsa_elem *get_elem_by_name(GArray *elems, const char *name);
+struct alsa_elem *get_elem_by_prefix(GArray *elems, const char *prefix);
+int get_max_elem_by_name(
+  GArray *elems,
+  const char *prefix,
+  const char *needle
+);
 int is_elem_routing_snk(struct alsa_elem *elem);
 
 // add callback to alsa_elem callback list