diff --git a/qrexec/qrexec-client.c b/qrexec/qrexec-client.c
index 23ef834..ef04e19 100644
--- a/qrexec/qrexec-client.c
+++ b/qrexec/qrexec-client.c
@@ -30,7 +30,7 @@
 #include "qrexec.h"
 #include "libqrexec-utils.h"
 
-int connect_unix_socket(char *domname)
+int connect_unix_socket(const char *domname)
 {
 	int s, len;
 	struct sockaddr_un remote;
@@ -51,12 +51,12 @@ int connect_unix_socket(char *domname)
 	return s;
 }
 
-void do_exec(char *prog)
+void do_exec(const char *prog)
 {
 	execl("/bin/bash", "bash", "-c", prog, NULL);
 }
 
-int local_stdin_fd, local_stdout_fd;
+static int local_stdin_fd, local_stdout_fd;
 
 void do_exit(int code)
 {
@@ -70,7 +70,7 @@ void do_exit(int code)
 }
 
 
-void prepare_local_fds(char *cmdline)
+void prepare_local_fds(const char *cmdline)
 {
 	int pid;
 	if (!cmdline) {
@@ -83,7 +83,7 @@ void prepare_local_fds(char *cmdline)
 }
 
 
-void send_cmdline(int s, int type, char *cmdline)
+void send_cmdline(int s, int type, const char *cmdline)
 {
 	struct client_header hdr;
 	hdr.type = type;
@@ -190,7 +190,7 @@ void handle_daemon_data(int s)
 
 // perhaps we could save a syscall if we include both sides in both
 // rdset and wrset; to be investigated
-void handle_daemon_only_until_writable(s)
+void handle_daemon_only_until_writable(int s)
 {
 	fd_set rdset, wrset;
 
@@ -235,7 +235,7 @@ void select_loop(int s)
 	}
 }
 
-void usage(char *name)
+void usage(const char *name)
 {
 	fprintf(stderr,
 		"usage: %s -d domain_num [-l local_prog] -e -c remote_cmdline\n"
diff --git a/qrexec/qrexec-daemon.c b/qrexec/qrexec-daemon.c
index c32e359..0365268 100644
--- a/qrexec/qrexec-daemon.c
+++ b/qrexec/qrexec-daemon.c
@@ -87,7 +87,7 @@ void sigchld_handler(int x);
 
 char *remote_domain_name;	// guess what
 
-int create_qrexec_socket(int domid, char *domname)
+int create_qrexec_socket(int domid, const char *domname)
 {
 	char socket_address[40];
 	char link_to_socket_name[strlen(domname) + sizeof(socket_address)];
@@ -222,7 +222,7 @@ void init(int xid)
 	kill(getppid(), SIGUSR1);	// let the parent know we are ready
 }
 
-void handle_new_client()
+void handle_new_client(void)
 {
 	int fd = do_accept(qrexec_daemon_unix_socket_fd);
 	if (fd >= MAX_CLIENTS) {
@@ -435,7 +435,7 @@ void sigchld_handler(int x)
 }
 
 /* clean zombies, update children_count */
-void reap_children()
+void reap_children(void)
 {
 	int status;
 	while (waitpid(-1, &status, WNOHANG) > 0)
@@ -444,7 +444,7 @@ void reap_children()
 }
 
 /* too many children - wait for one of them to terminate */
-void wait_for_child()
+void wait_for_child(void)
 {
 	int status;
 	waitpid(-1, &status, 0);
@@ -452,7 +452,7 @@ void wait_for_child()
 }
 
 #define MAX_CHILDREN 10
-void check_children_count_and_wait_if_too_many()
+void check_children_count_and_wait_if_too_many(void)
 {
 	if (children_count > MAX_CHILDREN) {
 		fprintf(stderr,
@@ -487,7 +487,7 @@ void sanitize_name(char * untrusted_s_signed)
 Called when agent sends a message asking to execute a predefined command.
 */
 
-void handle_execute_predefined_command()
+void handle_execute_predefined_command(void)
 {
 	int i;
 	struct trigger_connect_params untrusted_params, params;
@@ -564,7 +564,7 @@ void sanitize_message_from_agent(struct server_header *untrusted_header)
 	}
 }
 
-void handle_message_from_agent()
+void handle_message_from_agent(void)
 {
 	struct client_header hdr;
 	struct server_header s_hdr, untrusted_s_hdr;