diff --git a/include/stage2_params.h b/include/stage2_params.h
index 20130f73..12972e73 100644
--- a/include/stage2_params.h
+++ b/include/stage2_params.h
@@ -41,7 +41,7 @@ struct stage2_ptr_holder {
     uint8_t dummy_idt[DUMMY_IDT_DESC_SIZE];
 } __attribute__((packed));
 
-struct stage2_parameter *stage2_get_parameters();
+struct stage2_parameter *stage2_get_parameters(void);
 void stage2_set_parameters(struct stage2_parameter *p, struct stage2_ptr_holder *holder);
 void stage2_copy_parameter(struct stage2_parameter *p);
 
diff --git a/src/boot_x86_fsp.c b/src/boot_x86_fsp.c
index 7ea52bc2..fdf9bbcf 100644
--- a/src/boot_x86_fsp.c
+++ b/src/boot_x86_fsp.c
@@ -151,7 +151,7 @@ static int get_top_address(uint64_t *top, struct efi_hob *hoblist)
  * \param ptr Pointer to the parameter to be passed to the invoked function.
  */
 static void change_stack_and_invoke(uint32_t new_stack,
-                                    void (*other_func)(void *))
+                                    void (*other_func)(void))
 {
     __asm__ volatile("movl %0, %%eax\n"
                      "mov %%eax, %%esp\n"
@@ -504,7 +504,7 @@ static int self_extend_pcr(void)
  *
  * \param ptr Pointer to a parameter structure.
  */
-static void memory_ready_entry()
+static void memory_ready_entry(void)
 {
     struct fsp_info_header *fsp_info;
     temp_ram_exit_cb TempRamExit;
diff --git a/src/pci.c b/src/pci.c
index 89fa3030..fa56a7c5 100644
--- a/src/pci.c
+++ b/src/pci.c
@@ -941,12 +941,12 @@ static void pci_dump_bus(uint8_t bus)
     }
 }
 
-void pci_dump_config_space()
+void pci_dump_config_space(void)
 {
     return pci_dump_bus(0);
 }
 #else
-void pci_dump_config_space() {};
+void pci_dump_config_space(void) {};
 #endif
 
 int pci_enum_do(void)
diff --git a/src/stage2_params.c b/src/stage2_params.c
index 9c8335d9..77ccc39b 100644
--- a/src/stage2_params.c
+++ b/src/stage2_params.c
@@ -79,7 +79,7 @@ void stage2_set_parameters(struct stage2_parameter *p, struct stage2_ptr_holder
     asm ("lidt %0\r\n" : : "m"(idt));
 }
 
-struct stage2_parameter *stage2_get_parameters()
+struct stage2_parameter *stage2_get_parameters(void)
 {
     struct stage2_parameter **ptr;
     struct idt_descriptor idt;
@@ -107,7 +107,7 @@ void stage2_copy_parameter(struct stage2_parameter *p)
  * to fill the parameters */
 struct stage2_parameter _stage2_params;
 
-struct stage2_parameter *stage2_get_parameters()
+struct stage2_parameter *stage2_get_parameters(void)
 {
     return &_stage2_params;
 }