diff --git a/include/efi_api.h b/include/efi_api.h
index 4389dbe..83fd12b 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -221,13 +221,15 @@
 			struct efi_mem_desc *virtmap);
 	efi_status_t (*convert_pointer)(unsigned long dbg, void **address);
 	efi_status_t (EFIAPI *get_variable)(u16 *variable_name,
-					    efi_guid_t *vendor, u32 *attributes,
+					    const efi_guid_t *vendor,
+					    u32 *attributes,
 					    efi_uintn_t *data_size, void *data);
 	efi_status_t (EFIAPI *get_next_variable_name)(
 			efi_uintn_t *variable_name_size,
-			u16 *variable_name, efi_guid_t *vendor);
+			u16 *variable_name, const efi_guid_t *vendor);
 	efi_status_t (EFIAPI *set_variable)(u16 *variable_name,
-					    efi_guid_t *vendor, u32 attributes,
+					    const efi_guid_t *vendor,
+					    u32 attributes,
 					    efi_uintn_t data_size, void *data);
 	efi_status_t (EFIAPI *get_next_high_mono_count)(
 			uint32_t *high_count);
diff --git a/include/efi_loader.h b/include/efi_loader.h
index 6323686..5420c99 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -510,15 +510,15 @@
 				 struct efi_system_table *systab);
 #endif
 
-efi_status_t EFIAPI efi_get_variable(u16 *variable_name, efi_guid_t *vendor,
-				     u32 *attributes, efi_uintn_t *data_size,
-				     void *data);
+efi_status_t EFIAPI efi_get_variable(u16 *variable_name,
+				     const efi_guid_t *vendor, u32 *attributes,
+				     efi_uintn_t *data_size, void *data);
 efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
 					       u16 *variable_name,
-					       efi_guid_t *vendor);
-efi_status_t EFIAPI efi_set_variable(u16 *variable_name, efi_guid_t *vendor,
-				     u32 attributes, efi_uintn_t data_size,
-				     void *data);
+					       const efi_guid_t *vendor);
+efi_status_t EFIAPI efi_set_variable(u16 *variable_name,
+				     const efi_guid_t *vendor, u32 attributes,
+				     efi_uintn_t data_size, void *data);
 
 /*
  * See section 3.1.3 in the v2.7 UEFI spec for more details on
diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
index 19d9cb8..4e6a04e 100644
--- a/lib/efi_loader/efi_variable.c
+++ b/lib/efi_loader/efi_variable.c
@@ -99,7 +99,7 @@
 }
 
 static efi_status_t efi_to_native(char **native, const u16 *variable_name,
-				  efi_guid_t *vendor)
+				  const efi_guid_t *vendor)
 {
 	size_t len;
 	char *pos;
@@ -163,9 +163,9 @@
 }
 
 /* http://wiki.phoenix.com/wiki/index.php/EFI_RUNTIME_SERVICES#GetVariable.28.29 */
-efi_status_t EFIAPI efi_get_variable(u16 *variable_name, efi_guid_t *vendor,
-				     u32 *attributes, efi_uintn_t *data_size,
-				     void *data)
+efi_status_t EFIAPI efi_get_variable(u16 *variable_name,
+				     const efi_guid_t *vendor, u32 *attributes,
+				     efi_uintn_t *data_size, void *data)
 {
 	char *native_name;
 	efi_status_t ret;
@@ -244,7 +244,7 @@
 /* http://wiki.phoenix.com/wiki/index.php/EFI_RUNTIME_SERVICES#GetNextVariableName.28.29 */
 efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
 					       u16 *variable_name,
-					       efi_guid_t *vendor)
+					       const efi_guid_t *vendor)
 {
 	EFI_ENTRY("%p \"%ls\" %pUl", variable_name_size, variable_name, vendor);
 
@@ -252,9 +252,9 @@
 }
 
 /* http://wiki.phoenix.com/wiki/index.php/EFI_RUNTIME_SERVICES#SetVariable.28.29 */
-efi_status_t EFIAPI efi_set_variable(u16 *variable_name, efi_guid_t *vendor,
-				     u32 attributes, efi_uintn_t data_size,
-				     void *data)
+efi_status_t EFIAPI efi_set_variable(u16 *variable_name,
+				     const efi_guid_t *vendor, u32 attributes,
+				     efi_uintn_t data_size, void *data)
 {
 	char *native_name = NULL, *val = NULL, *s;
 	efi_status_t ret = EFI_SUCCESS;
diff --git a/lib/efi_selftest/efi_selftest_variables.c b/lib/efi_selftest/efi_selftest_variables.c
index e4c389a..ffc8cad 100644
--- a/lib/efi_selftest/efi_selftest_variables.c
+++ b/lib/efi_selftest/efi_selftest_variables.c
@@ -15,10 +15,10 @@
 
 static struct efi_boot_services *boottime;
 static struct efi_runtime_services *runtime;
-static efi_guid_t guid_vendor0 =
+static const efi_guid_t guid_vendor0 =
 	EFI_GUID(0x67029eb5, 0x0af2, 0xf6b1,
 		 0xda, 0x53, 0xfc, 0xb5, 0x66, 0xdd, 0x1c, 0xe6);
-static efi_guid_t guid_vendor1 =
+static const efi_guid_t guid_vendor1 =
 	EFI_GUID(0xff629290, 0x1fc1, 0xd73f,
 		 0x8f, 0xb1, 0x32, 0xf9, 0x0c, 0xa0, 0x42, 0xea);