diff --git a/bl31/bl31_main.c b/bl31/bl31_main.c
index 8cc7e0d..d949a08 100644
--- a/bl31/bl31_main.c
+++ b/bl31/bl31_main.c
@@ -56,7 +56,7 @@
 /*******************************************************************************
  * Simple function to initialise all BL31 helper libraries.
  ******************************************************************************/
-void bl31_lib_init()
+void bl31_lib_init(void)
 {
 	cm_init();
 }
@@ -137,7 +137,7 @@
  * This function programs EL3 registers and performs other setup to enable entry
  * into the next image after BL31 at the next ERET.
  ******************************************************************************/
-void bl31_prepare_next_image_entry()
+void bl31_prepare_next_image_entry(void)
 {
 	entry_point_info_t *next_image_info;
 	uint32_t image_type;
diff --git a/bl31/context_mgmt.c b/bl31/context_mgmt.c
index 81c7c56..65f1213 100644
--- a/bl31/context_mgmt.c
+++ b/bl31/context_mgmt.c
@@ -56,7 +56,7 @@
  * which will used for programming an entry into a lower EL. The same context
  * will used to save state upon exception entry from that EL.
  ******************************************************************************/
-void cm_init()
+void cm_init(void)
 {
 	/*
 	 * The context management library has only global data to intialize, but
diff --git a/bl31/runtime_svc.c b/bl31/runtime_svc.c
index 08cd2d8..c33748f 100644
--- a/bl31/runtime_svc.c
+++ b/bl31/runtime_svc.c
@@ -78,7 +78,7 @@
  * The unique oen is used as an index into the 'rt_svc_descs_indices' array.
  * The index of the runtime service descriptor is stored at this index.
  ******************************************************************************/
-void runtime_svc_init()
+void runtime_svc_init(void)
 {
 	int32_t rc = 0;
 	uint32_t index, start_idx, end_idx;