diff --git a/inc/backend.h b/inc/backend.h
index a45dccd..abbf4bb 100644
--- a/inc/backend.h
+++ b/inc/backend.h
@@ -1,5 +1,5 @@
-#ifndef STLINK_BACKEND_H_
-#define STLINK_BACKEND_H_
+#ifndef BACKEND_H_
+#define BACKEND_H_
 
     typedef struct _stlink_backend {
         void (*close) (stlink_t * sl);
@@ -34,4 +34,4 @@
         int (*trace_read) (stlink_t * sl, uint8_t* buf, size_t size);
     } stlink_backend_t;
 
-#endif // STLINK_BACKEND_H_
+#endif // BACKEND_H_
diff --git a/inc/stlink.h b/inc/stlink.h
index b9379e0..2a19287 100644
--- a/inc/stlink.h
+++ b/inc/stlink.h
@@ -6,8 +6,8 @@
  * regardless of how the backend does the work....
  */
 
-#ifndef STLINK_H
-#define STLINK_H
+#ifndef STLINK_H_
+#define STLINK_H_
 
 #include <stdint.h>
 #include <stddef.h>
@@ -311,4 +311,4 @@ int stlink_target_connect(stlink_t *sl, enum connect_type connect);
 }
 #endif
 
-#endif // STLINK_H
+#endif // STLINK_H_
diff --git a/inc/stm32.h b/inc/stm32.h
index d3c4e55..abc7f1d 100644
--- a/inc/stm32.h
+++ b/inc/stm32.h
@@ -4,8 +4,8 @@
  * STM32-specific defines & identification parametres
  */
 
-#ifndef STM32_H
-#define STM32_H
+#ifndef STM32_H_
+#define STM32_H_
 
 /* STM32 Cortex-M core ids (CPUTAPID) */
 enum stm32_core_id {
@@ -217,4 +217,4 @@ enum stm32_chipids {
 #define STM32L5_PWR_CR1 0x40007000                      // RM0438, p. 93,324
 #define STM32L5_PWR_CR1_VOS 9
 
-#endif // STM32_H
+#endif // STM32_H_
diff --git a/inc/stm32flash.h b/inc/stm32flash.h
index 07f8248..f5f662c 100644
--- a/inc/stm32flash.h
+++ b/inc/stm32flash.h
@@ -1,5 +1,5 @@
-#ifndef STM32FLASH_H
-#define STM32FLASH_H
+#ifndef STM32FLASH_H_
+#define STM32FLASH_H_
 
 /* stm32f FPEC flash controller interface, pm0063 manual */
 // STM32F05x is identical, based on RM0091 (DM00031936, Doc ID 018940 Rev 2, August 2012)
@@ -378,4 +378,4 @@
 #define FLASH_H7_OPTSR_CUR (FLASH_H7_REGS_ADDR + 0x1c)
 #define FLASH_H7_OPTCCR (FLASH_H7_REGS_ADDR + 0x24)
 
-#endif // STM32FLASH_H
+#endif // STM32FLASH_H_
diff --git a/inc/version.h.in b/inc/version.h.in
index 66159e0..b5ccd6e 100644
--- a/inc/version.h.in
+++ b/inc/version.h.in
@@ -1,9 +1,9 @@
-#ifndef STLINK_VERSION_H_
-#define STLINK_VERSION_H_
+#ifndef VERSION_H_
+#define VERSION_H_
 
 #define STLINK_VERSION       "@PROJECT_VERSION@"
 #define STLINK_VERSION_MAJOR @PROJECT_VERSION_MAJOR@
 #define STLINK_VERSION_MINOR @PROJECT_VERSION_MINOR@
 #define STLINK_VERSION_PATCH @PROJECT_VERSION_PATCH@
 
-#endif // STLINK_VERSION_H_
+#endif // VERSION_H_
diff --git a/src/st-flash/flash.h b/src/st-flash/flash.h
index f3d431d..aab5787 100644
--- a/src/st-flash/flash.h
+++ b/src/st-flash/flash.h
@@ -1,5 +1,5 @@
-#ifndef STLINK_TOOLS_FLASH_H_
-#define STLINK_TOOLS_FLASH_H_
+#ifndef FLASH_H_
+#define FLASH_H_
 
 #include <stdint.h>
 
@@ -33,4 +33,4 @@ struct flash_opts {
 
 int flash_get_opts(struct flash_opts* o, int ac, char** av);
 
-#endif // STLINK_FLASH_H_
+#endif // FLASH_H_
diff --git a/src/st-util/gdb-remote.h b/src/st-util/gdb-remote.h
index 6e76746..bcf1dbd 100644
--- a/src/st-util/gdb-remote.h
+++ b/src/st-util/gdb-remote.h
@@ -1,8 +1,8 @@
-#ifndef _GDB_REMOTE_H_
-#define _GDB_REMOTE_H_
+#ifndef GDB_REMOTE_H_
+#define GDB_REMOTE_H_
 
 int gdb_send_packet(int fd, char* data);
 int gdb_recv_packet(int fd, char** buffer);
 int gdb_check_for_interrupt(int fd);
 
-#endif // _GDB_REMOTE_H_
+#endif // GDB_REMOTE_H_
diff --git a/src/st-util/gdb-server.h b/src/st-util/gdb-server.h
index b50a794..3fbb16d 100644
--- a/src/st-util/gdb-server.h
+++ b/src/st-util/gdb-server.h
@@ -1,5 +1,5 @@
-#ifndef _GDB_SERVER_H
-#define _GDB_SERVER_H
+#ifndef GDB_SERVER_H_
+#define GDB_SERVER_H_
 
 #define STRINGIFY_inner(name) #name
 #define STRINGIFY(name) STRINGIFY_inner(name)
@@ -8,4 +8,4 @@
 #define DEBUG_LOGGING_LEVEL 100
 #define DEFAULT_GDB_LISTEN_PORT 4242
 
-#endif // _GDB_SERVER_H
+#endif // GDB_SERVER_H_
diff --git a/src/st-util/semihosting.h b/src/st-util/semihosting.h
index 8c1ac15..2e34b43 100644
--- a/src/st-util/semihosting.h
+++ b/src/st-util/semihosting.h
@@ -1,5 +1,5 @@
-#ifndef _SEMIHOSTING_H_
-#define _SEMIHOSTING_H_
+#ifndef SEMIHOSTING_H_
+#define SEMIHOSTING_H_
 
 #include <stlink.h>
 
@@ -31,4 +31,4 @@
 
 int do_semihosting(stlink_t *sl, uint32_t r0, uint32_t r1, uint32_t *ret);
 
-#endif // _SEMIHOSTING_H_
+#endif // SEMIHOSTING_H_
diff --git a/src/stlink-gui/gui.h b/src/stlink-gui/gui.h
index b3d5dff..f29ee50 100644
--- a/src/stlink-gui/gui.h
+++ b/src/stlink-gui/gui.h
@@ -1,5 +1,5 @@
-#ifndef __STLINK_GUI_H__
-#define __STLINK_GUI_H__
+#ifndef GUI_H_
+#define GUI_H_
 
 #include <glib-object.h>
 
@@ -89,4 +89,4 @@ struct _STlinkGUIClass {
 GType stlink_gui_get_type(void);
 int export_to_file(const char*filename, const struct mem_t flash_mem);
 
-#endif // __STLINK_GUI_H__
+#endif // GUI_H_
diff --git a/src/stlink-lib/calculate.h b/src/stlink-lib/calculate.h
index 64dfb51..beb0642 100644
--- a/src/stlink-lib/calculate.h
+++ b/src/stlink-lib/calculate.h
@@ -4,12 +4,12 @@
  * Calculation of sector numbers and pages
  */
 
-#ifndef CALCULATE_H
-#define CALCULATE_H
+#ifndef CALCULATE_H_
+#define CALCULATE_H_
 
 uint32_t calculate_F4_sectornum(uint32_t);
 uint32_t calculate_F7_sectornum(uint32_t);
 uint32_t calculate_H7_sectornum(stlink_t *, uint32_t, unsigned);
 uint32_t calculate_L4_page(stlink_t *, uint32_t);
 
-#endif // CALCULATE_H
+#endif // CALCULATE_H_
diff --git a/src/stlink-lib/chipid.h b/src/stlink-lib/chipid.h
index 1eae2cc..b93a3f2 100644
--- a/src/stlink-lib/chipid.h
+++ b/src/stlink-lib/chipid.h
@@ -1,5 +1,5 @@
-#ifndef STLINK_CHIPID_H_
-#define STLINK_CHIPID_H_
+#ifndef CHIPID_H_
+#define CHIPID_H_
 
 #include <stm32.h>
 #include <stlink.h>
@@ -24,4 +24,4 @@ struct stlink_chipid_params {
 struct stlink_chipid_params *stlink_chipid_get_params(uint32_t chipid);
   void init_chipids(char *dir_to_scan);
 
-#endif // STLINK_CHIPID_H_
+#endif // CHIPID_H_
diff --git a/src/stlink-lib/commands.h b/src/stlink-lib/commands.h
index 136adf8..4fa9198 100644
--- a/src/stlink-lib/commands.h
+++ b/src/stlink-lib/commands.h
@@ -1,5 +1,5 @@
-#ifndef STLINK_COMMANDS_H_
-#define STLINK_COMMANDS_H_
+#ifndef COMMANDS_H_
+#define COMMANDS_H_
 
 enum stlink_commands {
     STLINK_GET_VERSION                   = 0xF1,
@@ -54,4 +54,4 @@ enum stlink_dfu_commands {
     STLINK_DFU_EXIT                      = 0x07
 };
 
-#endif // STLINK_COMMANDS_H_
+#endif // COMMANDS_H_
diff --git a/src/stlink-lib/common.h b/src/stlink-lib/common.h
index dd6cf95..9024936 100644
--- a/src/stlink-lib/common.h
+++ b/src/stlink-lib/common.h
@@ -4,12 +4,12 @@
  * General helper functions
  */
 
-#ifndef COMMON_H
-#define COMMON_H
+#ifndef COMMON_H_
+#define COMMON_H_
 
 int check_file(stlink_t *, mapped_file_t *, stm32_addr_t);
 void md5_calculate(mapped_file_t *);
 void stlink_checksum(mapped_file_t *);
 void stlink_fwrite_finalize(stlink_t *, stm32_addr_t);
 
-#endif // COMMON_H
+#endif // COMMON_H_
diff --git a/src/stlink-lib/common_flash.h b/src/stlink-lib/common_flash.h
index 3b6b040..269f819 100644
--- a/src/stlink-lib/common_flash.h
+++ b/src/stlink-lib/common_flash.h
@@ -4,8 +4,8 @@
  * Flash operations
  */
 
-#ifndef COMMON_FLASH_H
-#define COMMON_FLASH_H
+#ifndef COMMON_FLASH_H_
+#define COMMON_FLASH_H_
 
 void lock_flash(stlink_t *);
 void clear_flash_error(stlink_t *);
@@ -24,4 +24,5 @@ void clear_flash_cr_pg(stlink_t *, unsigned);
 
 uint32_t read_flash_cr(stlink_t *, unsigned);
 uint32_t get_stm32l0_flash_base(stlink_t *);
-#endif // STLINK_H
+
+#endif // COMMON_FLASH_H_
diff --git a/src/stlink-lib/flash_loader.h b/src/stlink-lib/flash_loader.h
index 0d39a9a..781fab7 100644
--- a/src/stlink-lib/flash_loader.h
+++ b/src/stlink-lib/flash_loader.h
@@ -4,8 +4,8 @@
  * Flash loader
  */
  
-#ifndef STLINK_FLASH_LOADER_H_
-#define STLINK_FLASH_LOADER_H_
+#ifndef FLASH_LOADER_H_
+#define FLASH_LOADER_H_
 
 #include <stdio.h>
 #include <stdint.h>
@@ -21,4 +21,4 @@ int stlink_flashloader_start(stlink_t *sl, flash_loader_t *fl);
 int stlink_flashloader_write(stlink_t *sl, flash_loader_t *fl, stm32_addr_t addr, uint8_t* base, uint32_t len);
 int stlink_flashloader_stop(stlink_t *sl, flash_loader_t *fl);
 
-#endif // STLINK_FLASH_LOADER_H_
+#endif // FLASH_LOADER_H_
diff --git a/src/stlink-lib/helper.h b/src/stlink-lib/helper.h
index 9646737..58023af 100644
--- a/src/stlink-lib/helper.h
+++ b/src/stlink-lib/helper.h
@@ -1,8 +1,8 @@
-#ifndef SYS_HELPER_H
-#define SYS_HELPER_H
+#ifndef HELPER_H_
+#define HELPER_H_
 
 unsigned time_ms();
 
 int arg_parse_freq(const char *str);
 
-#endif /* SYS_HELPER_H */
+#endif // HELPER_H_
diff --git a/src/stlink-lib/libusb_settings.h b/src/stlink-lib/libusb_settings.h
index 3777f72..639f9e4 100644
--- a/src/stlink-lib/libusb_settings.h
+++ b/src/stlink-lib/libusb_settings.h
@@ -1,5 +1,5 @@
-#ifndef LIBUSB_SETTINGS_H
-#define LIBUSB_SETTINGS_H
+#ifndef LIBUSB_SETTINGS_H_
+#define LIBUSB_SETTINGS_H_
 
 #include <libusb.h>
 
@@ -44,4 +44,4 @@
     #error unsupported libusb version
 #endif
 
-#endif // LIBUSB_SETTINGS_H
+#endif // LIBUSB_SETTINGS_H_
diff --git a/src/stlink-lib/logging.h b/src/stlink-lib/logging.h
index 7f39944..7510d57 100644
--- a/src/stlink-lib/logging.h
+++ b/src/stlink-lib/logging.h
@@ -2,8 +2,8 @@
  * Ugly, low performance, configurable level, logging "framework"
  */
 
-#ifndef UGLYLOGGING_H
-#define UGLYLOGGING_H
+#ifndef LOGGING_H_
+#define LOGGING_H_
 
 #ifdef  __cplusplus
 extern "C" {
@@ -45,4 +45,4 @@ int ugly_libusb_log_level(enum ugly_loglevel v);
 }
 #endif
 
-#endif  // UGLYLOGGING_H
+#endif  // LOGGING_H_
diff --git a/src/stlink-lib/map_file.h b/src/stlink-lib/map_file.h
index f50a201..d69f6c3 100644
--- a/src/stlink-lib/map_file.h
+++ b/src/stlink-lib/map_file.h
@@ -4,8 +4,8 @@
  * File mapping
  */
 
-#ifndef MAP_FILE_H
-#define MAP_FILE_H
+#ifndef MAP_FILE_H_
+#define MAP_FILE_H_
 
 #ifndef O_BINARY
 #define O_BINARY 0
@@ -29,4 +29,4 @@ typedef struct mapped_file {
 int map_file(mapped_file_t *, const char *);
 void unmap_file(mapped_file_t *);
 
-#endif // MAP_FILE_H
+#endif // MAP_FILE_H_
diff --git a/src/stlink-lib/md5.h b/src/stlink-lib/md5.h
index a69d7fc..7b853a4 100644
--- a/src/stlink-lib/md5.h
+++ b/src/stlink-lib/md5.h
@@ -5,6 +5,15 @@
  * This is free and unencumbered software released into the public domain - June 2013 - waterjuice.org
  */
 
+/*
+ * File: md5.h
+ *
+ * MD5 hash function
+ */
+
+#ifndef MD5_H_
+#define MD5_H_
+
 #pragma once
 
 #include <stdint.h>
@@ -61,3 +70,5 @@ void Md5Finalise(Md5Context* Context /* [in out] */, MD5_HASH* Digest /* [in] */
  * Calculates the MD5 hash of the buffer.
  */
 void Md5Calculate(void const* Buffer /* [in] */, uint32_t BufferSize /* [in] */, MD5_HASH* Digest /* [in] */);
+
+#endif // MD5_H_
\ No newline at end of file
diff --git a/src/stlink-lib/option_bytes.h b/src/stlink-lib/option_bytes.h
index b9f88c5..481a69f 100644
--- a/src/stlink-lib/option_bytes.h
+++ b/src/stlink-lib/option_bytes.h
@@ -4,6 +4,9 @@
  * Read and write option bytes and option control registers
  */
 
+#ifndef OPTION_BYTES_H_
+#define OPTION_BYTES_H_
+
 #include <stdio.h>
 #include <stlink.h>
 
@@ -19,3 +22,5 @@ int stlink_write_option_control_register1_32(stlink_t *sl, uint32_t option_cr1);
 
 int stlink_write_option_bytes(stlink_t *sl, stm32_addr_t addr, uint8_t* base, uint32_t len);
 int stlink_fwrite_option_bytes(stlink_t *sl, const char* path, stm32_addr_t addr);
+
+#endif // OPTION_BYTES_H_
\ No newline at end of file
diff --git a/src/stlink-lib/reg.h b/src/stlink-lib/reg.h
index b581a26..2046f8a 100644
--- a/src/stlink-lib/reg.h
+++ b/src/stlink-lib/reg.h
@@ -1,5 +1,5 @@
-#ifndef STLINK_REG_H_
-#define STLINK_REG_H_
+#ifndef REG_H_
+#define REG_H_
 
 #define STLINK_REG_CM3_CPUID                0xE000ED00
 
@@ -123,4 +123,4 @@
 #define STLINK_REG_CM7_ICIALLU              0xE000EF50
 #define STLINK_REG_CM7_CCSIDR               0xE000ED80
 
-#endif // STLINK_REG_H_
+#endif // REG_H_
diff --git a/src/stlink-lib/sg.h b/src/stlink-lib/sg.h
index 212d03b..e30043f 100644
--- a/src/stlink-lib/sg.h
+++ b/src/stlink-lib/sg.h
@@ -3,8 +3,8 @@
  * Author: karl
  */
 
-#ifndef STLINK_SG_H
-#define STLINK_SG_H
+#ifndef SG_H_
+#define SG_H_
 
 #include <stlink.h>
 #include <libusb_settings.h>
@@ -56,4 +56,4 @@ struct stlink_libsg {
 
 stlink_t* stlink_v1_open(const int verbose, int reset);
 
-#endif // STLINK_SG_H
+#endif // SG_H_
diff --git a/src/stlink-lib/usb.h b/src/stlink-lib/usb.h
index 3f4b71e..ff6f908 100644
--- a/src/stlink-lib/usb.h
+++ b/src/stlink-lib/usb.h
@@ -3,8 +3,8 @@
  * Author: karl
  */
 
-#ifndef STLINK_USB_H
-#define STLINK_USB_H
+#ifndef USB_H_
+#define USB_H_
 
 #include <stdbool.h>
 
@@ -70,4 +70,4 @@ stlink_t *stlink_open_usb(enum ugly_loglevel verbose, enum connect_type connect,
 size_t stlink_probe_usb(stlink_t **stdevs[], enum connect_type connect, int freq);
 void stlink_probe_usb_free(stlink_t **stdevs[], size_t size);
 
-#endif // STLINK_USB_H
+#endif // USB_H_
diff --git a/src/win32/getopt/getopt.h b/src/win32/getopt/getopt.h
index 3aaf73b..2a1bd73 100644
--- a/src/win32/getopt/getopt.h
+++ b/src/win32/getopt/getopt.h
@@ -1,5 +1,5 @@
-#ifndef INCLUDED_GETOPT_PORT_H
-#define INCLUDED_GETOPT_PORT_H
+#ifndef GETOPT_H_
+#define GETOPT_H_
 
 #if defined(__cplusplus)
 extern "C" {
@@ -38,4 +38,4 @@ int getopt_long(int argc,
 }
 #endif
 
-#endif // INCLUDED_GETOPT_PORT_H
+#endif // GETOPT_H_
diff --git a/src/win32/mmap.h b/src/win32/mmap.h
index 06079a9..ff01f42 100644
--- a/src/win32/mmap.h
+++ b/src/win32/mmap.h
@@ -1,5 +1,5 @@
-#ifndef STLINK_MMAP_H
-#define STLINK_MMAP_H
+#ifndef MMAP_H_
+#define MMAP_H_
 
 #ifdef STLINK_HAVE_SYS_MMAN_H
 #include <sys/mman.h>
@@ -16,6 +16,6 @@
 void *mmap(void *addr, size_t len, int prot, int flags, int fd, long long offset);
 int munmap(void *addr, size_t len);
 
-#endif /* HAVE_SYS_MMAN_H */
+#endif // STLINK_HAVE_SYS_MMAN_H
 
-#endif /* STLINK_MMAP_H */
+#endif // MMAP_H_
diff --git a/src/win32/sys_time.h b/src/win32/sys_time.h
index d314509..cb767fc 100644
--- a/src/win32/sys_time.h
+++ b/src/win32/sys_time.h
@@ -1,8 +1,10 @@
-#ifndef STLINK_TIME_H
-#define STLINK_TIME_H
+#ifndef SYS_TIME_H_
+#define SYS_TIME_H_
 
 #ifdef STLINK_HAVE_SYS_TIME_H
+
 #include <sys/time.h>
+
 #else
 
 #include <windows.h>
@@ -14,6 +16,6 @@ struct timezone {
 
 int gettimeofday(struct timeval *tv, struct timezone *tz);
 
-#endif /* STLINK_HAVE_SYS_TIME_H */
+#endif // STLINK_HAVE_SYS_TIME_H
 
-#endif /* STLINK_TIME_H */
+#endif // SYS_TIME_H_
diff --git a/src/win32/unistd/unistd.h b/src/win32/unistd/unistd.h
index 389c446..b8a3db7 100644
--- a/src/win32/unistd/unistd.h
+++ b/src/win32/unistd/unistd.h
@@ -1,5 +1,5 @@
-#ifndef _UNISTD_H
-#define _UNISTD_H    1
+#ifndef UNISTD_H_
+#define UNISTD_H_
 
 /*
  * This file intended to serve as a drop-in replacement for unistd.h on Windows
@@ -72,4 +72,4 @@ typedef unsigned __int64 uint64_t;
 int usleep(unsigned int waitTime);
 #endif
 
-#endif // _UNISTD_H
+#endif // UNISTD_H_