diff --git a/programs/ssl/ssl_context_info.c b/programs/ssl/ssl_context_info.c
index a5f0650..855b091 100644
--- a/programs/ssl/ssl_context_info.c
+++ b/programs/ssl/ssl_context_info.c
@@ -125,12 +125,12 @@
 /*
  * Basic printing functions
  */
-void print_version()
+void print_version(void)
 {
     printf("%s v%d.%d\n", PROG_NAME, VER_MAJOR, VER_MINOR);
 }
 
-void print_usage()
+void print_usage(void)
 {
     print_version();
     printf("\nThis program is used to deserialize an Mbed TLS SSL session from the base64 code provided\n"
@@ -179,7 +179,7 @@
 /*
  * Exit from the program in case of error
  */
-void error_exit()
+void error_exit(void)
 {
     if (NULL != b64_file) {
         fclose(b64_file);