diff --git a/core/dive.c b/core/dive.c
index 7866962d4..b7ce01ea4 100644
--- a/core/dive.c
+++ b/core/dive.c
@@ -205,7 +205,7 @@ void remove_event(struct event *event)
  * have to actually remove the existing event and replace it with a new one.
  * WARNING, WARNING... this may end up freeing event in case that event is indeed
  * WARNING, WARNING... part of this divecomputer on this dive! */
-void update_event_name(struct dive *d, struct event *event, char *name)
+void update_event_name(struct dive *d, struct event *event, const char *name)
 {
 	if (!d || !event)
 		return;
@@ -3633,7 +3633,7 @@ timestamp_t get_times()
 	return dive->when;
 }
 
-void set_userid(char *rUserId)
+void set_userid(const char *rUserId)
 {
 	char *userid = strdup(rUserId);
 	if (strlen(userid) > 30)
@@ -3653,7 +3653,7 @@ void set_userid(char *rUserId)
  * functionality for the core library that Subsurface itself doesn't
  * use but that another consumer of the library (like an HTML exporter)
  * will need */
-void set_informational_units(char *units)
+void set_informational_units(const char *units)
 {
 	if (strstr(units, "METRIC")) {
 		git_prefs.unit_system = METRIC;
@@ -3691,7 +3691,7 @@ void set_informational_units(char *units)
 
 }
 
-void set_git_prefs(char *prefs)
+void set_git_prefs(const char *prefs)
 {
 	if (strstr(prefs, "TANKBAR"))
 		git_prefs.tankbar = 1;
@@ -3850,7 +3850,7 @@ struct picture *clone_picture(struct picture *src)
 }
 
 // Return true if picture was found and deleted
-bool dive_remove_picture(struct dive *d, char *filename)
+bool dive_remove_picture(struct dive *d, const char *filename)
 {
 	struct picture **picture = &d->picture_list;
 	while (*picture && !same_string((*picture)->filename, filename))
diff --git a/core/dive.h b/core/dive.h
index 56b0fbcfc..a1cb7fb60 100644
--- a/core/dive.h
+++ b/core/dive.h
@@ -430,7 +430,7 @@ extern struct picture *clone_picture(struct picture *src);
 extern bool dive_check_picture_time(struct dive *d, int shift_time, timestamp_t timestamp);
 extern void dive_create_picture(struct dive *d, const char *filename, int shift_time, bool match_all);
 extern void dive_add_picture(struct dive *d, struct picture *newpic);
-extern bool dive_remove_picture(struct dive *d, char *filename);
+extern bool dive_remove_picture(struct dive *d, const char *filename);
 extern unsigned int dive_get_picture_count(struct dive *d);
 extern bool picture_check_valid(const char *filename, int shift_time);
 extern void picture_load_exif_data(struct picture *p);
@@ -816,7 +816,7 @@ extern void fill_default_cylinder(cylinder_t *cyl);
 extern void add_gas_switch_event(struct dive *dive, struct divecomputer *dc, int time, int idx);
 extern struct event *add_event(struct divecomputer *dc, unsigned int time, int type, int flags, int value, const char *name);
 extern void remove_event(struct event *event);
-extern void update_event_name(struct dive *d, struct event* event, char *name);
+extern void update_event_name(struct dive *d, struct event* event, const char *name);
 extern void add_extra_data(struct divecomputer *dc, const char *key, const char *value);
 extern void per_cylinder_mean_depth(struct dive *dive, struct divecomputer *dc, int *mean, int *duration);
 extern int get_cylinder_index(struct dive *dive, struct event *ev);
@@ -1011,9 +1011,9 @@ extern double strtod_flags(const char *str, const char **ptr, unsigned int flags
 
 #define ascii_strtod(str, ptr) strtod_flags(str, ptr, STRTOD_ASCII)
 
-extern void set_userid(char *user_id);
-extern void set_informational_units(char *units);
-extern void set_git_prefs(char *prefs);
+extern void set_userid(const char *user_id);
+extern void set_informational_units(const char *units);
+extern void set_git_prefs(const char *prefs);
 
 extern const char *get_dive_date_c_string(timestamp_t when);
 extern void update_setpoint_events(struct dive *dive, struct divecomputer *dc);