diff --git a/src/lib.c b/src/lib.c
index 1a1de75..51367c6 100644
--- a/src/lib.c
+++ b/src/lib.c
@@ -128,7 +128,7 @@ uint8_t add_rds_af(RDSAFs *af_list, float freq) {
 	return 0;
 }
 
-char *convert_to_rdscharset(char *str) {
+char *convert_to_rdscharset(const char *str) {
 	static char new_str[255];
 	uint8_t i = 0;
 
diff --git a/src/lib.h b/src/lib.h
index 90ce187..b2e11d4 100644
--- a/src/lib.h
+++ b/src/lib.h
@@ -16,4 +16,4 @@ uint16_t get_block_from_group(RDSGroup *group, uint8_t block);
 void add_checkwords(RDSGroup *group, uint8_t *bits);
 uint8_t add_rds_af_oda(RDSAFsODA *af_list, float freq);
 uint8_t add_rds_af(RDSAFs *af_list, float freq);
-char *convert_to_rdscharset(char *str);
\ No newline at end of file
+char *convert_to_rdscharset(const char *str);
\ No newline at end of file
diff --git a/src/rds.c b/src/rds.c
index 96ff973..6b2db46 100644
--- a/src/rds.c
+++ b/src/rds.c
@@ -706,7 +706,7 @@ void init_rds_encoder(RDSEncoder* enc) {
 	for(int i = 0; i < PROGRAMS; i++) reset_rds_state(enc, i);
 }
 
-void set_rds_rt1(RDSEncoder* enc, char *rt1) {
+void set_rds_rt1(RDSEncoder* enc, const char *rt1) {
 	uint8_t i = 0, len = 0;
 
 	enc->state[enc->program].rt_text_timeout_state = enc->data[enc->program].rt_text_timeout;
@@ -728,7 +728,7 @@ void set_rds_rt1(RDSEncoder* enc, char *rt1) {
 	} else enc->state[enc->program].rt_segments = 16;
 }
 
-void set_rds_rt2(RDSEncoder* enc, char *rt2) {
+void set_rds_rt2(RDSEncoder* enc, const char *rt2) {
 	uint8_t i = 0, len = 0;
 
 	enc->state[enc->program].rt2_update = 1;
@@ -748,7 +748,7 @@ void set_rds_rt2(RDSEncoder* enc, char *rt2) {
 	} else enc->state[enc->program].rt2_segments = 16;
 }
 
-void set_rds_ps(RDSEncoder* enc, char *ps) {
+void set_rds_ps(RDSEncoder* enc, const char *ps) {
 	uint8_t len = 0;
 
 	enc->state[enc->program].ps_update = 1;
@@ -756,7 +756,7 @@ void set_rds_ps(RDSEncoder* enc, char *ps) {
 	while (*ps != 0 && len < PS_LENGTH) enc->data[enc->program].ps[len++] = *ps++;
 }
 
-void set_rds_tps(RDSEncoder* enc, char *tps) {
+void set_rds_tps(RDSEncoder* enc, const char *tps) {
 	uint8_t len = 0;
 
 	enc->state[enc->program].tps_update = 1;
@@ -769,7 +769,7 @@ void set_rds_tps(RDSEncoder* enc, char *tps) {
 	while (*tps != 0 && len < PS_LENGTH) enc->data[enc->program].tps[len++] = *tps++;
 }
 
-void set_rds_lps(RDSEncoder* enc, char *lps) {
+void set_rds_lps(RDSEncoder* enc, const char *lps) {
 	uint8_t i = 0, len = 0;
 
 	enc->state[enc->program].lps_update = 1;
@@ -790,7 +790,7 @@ void set_rds_lps(RDSEncoder* enc, char *lps) {
 	} else enc->state[enc->program].lps_segments = 8;
 }
 
-void set_rds_ert(RDSEncoder* enc, char *ert) {
+void set_rds_ert(RDSEncoder* enc, const char *ert) {
 	uint8_t i = 0, len = 0;
 
 	enc->state[enc->program].ert_update = 1;
@@ -850,7 +850,7 @@ void set_rds_ptyn(RDSEncoder* enc, const char *ptyn) {
 	while (*ptyn != 0 && len < PTYN_LENGTH) enc->data[enc->program].ptyn[len++] = *ptyn++;
 }
 
-void set_rds_grpseq(RDSEncoder* enc, char *grpseq) {
+void set_rds_grpseq(RDSEncoder* enc, const char *grpseq) {
 	uint8_t len = 0;
 
 	if(grpseq[0] == '\0') {
@@ -864,7 +864,7 @@ void set_rds_grpseq(RDSEncoder* enc, char *grpseq) {
 	memset(enc->data[enc->program].grp_sqc, 0, 24);
 	while (*grpseq != 0 && len < 24) enc->data[enc->program].grp_sqc[len++] = *grpseq++;
 }
-void set_rds_grpseq2(RDSEncoder* enc, char *grpseq2) {
+void set_rds_grpseq2(RDSEncoder* enc, const char *grpseq2) {
 	uint8_t len = 0;
 
 	if(grpseq2[0] == '\0') {
diff --git a/src/rds.h b/src/rds.h
index dbbf09b..720d19e 100644
--- a/src/rds.h
+++ b/src/rds.h
@@ -238,14 +238,14 @@ void set_rds_defaults(RDSEncoder* enc, uint8_t program);
 void init_rds_encoder(RDSEncoder* enc);
 void get_rds_bits(RDSEncoder* enc, uint8_t *bits, uint8_t stream);
 
-void set_rds_rt1(RDSEncoder* enc, char *rt1);
-void set_rds_rt2(RDSEncoder* enc, char *rt2);
-void set_rds_ps(RDSEncoder* enc, char *ps);
-void set_rds_tps(RDSEncoder* enc, char *tps);
-void set_rds_lps(RDSEncoder* enc, char *lps);
-void set_rds_ert(RDSEncoder *enc, char *ert);
+void set_rds_rt1(RDSEncoder* enc, const char *rt1);
+void set_rds_rt2(RDSEncoder* enc, const char *rt2);
+void set_rds_ps(RDSEncoder* enc, const char *ps);
+void set_rds_tps(RDSEncoder* enc, const char *tps);
+void set_rds_lps(RDSEncoder* enc, const char *lps);
+void set_rds_ert(RDSEncoder *enc, const char *ert);
 void set_rds_rtplus_tags(RDSEncoder *enc, uint8_t *tags);
 void set_rds_ertplus_tags(RDSEncoder *enc, uint8_t *tags);
 void set_rds_ptyn(RDSEncoder *enc, const char *ptyn);
-void set_rds_grpseq(RDSEncoder* enc, char *grpseq);
-void set_rds_grpseq2(RDSEncoder* enc, char *grpseq2);
\ No newline at end of file
+void set_rds_grpseq(RDSEncoder* enc, const char *grpseq);
+void set_rds_grpseq2(RDSEncoder* enc, const char *grpseq2);
\ No newline at end of file