diff --git a/src/usbasp.h b/src/usbasp.h
index 853c6d90..1387e9a3 100644
--- a/src/usbasp.h
+++ b/src/usbasp.h
@@ -19,7 +19,7 @@
 #ifndef usbasp_h
 #define usbasp_h
 
-/* USB function call identifiers */
+// USB function call identifiers
 #define USBASP_FUNC_CONNECT    1
 #define USBASP_FUNC_DISCONNECT 2
 #define USBASP_FUNC_TRANSMIT   3
@@ -38,35 +38,35 @@
 #define USBASP_FUNC_TPI_WRITEBLOCK   16
 #define USBASP_FUNC_GETCAPABILITIES 127
 
-/* USBASP capabilities */
+// USBASP capabilities
 #define USBASP_CAP_TPI    0x01
-#define USBASP_CAP_3MHZ   (1 << 24)   // 3 MHz SCK in UsbAsp-flash firmware
+#define USBASP_CAP_3MHZ   (1 << 24)     // 3 MHz SCK in UsbAsp-flash firmware
 
-/* Block mode flags */
+// Block mode flags
 #define USBASP_BLOCKFLAG_FIRST    1
 #define USBASP_BLOCKFLAG_LAST     2
 
-/* Block mode data size */
+// Block mode data size
 #define USBASP_READBLOCKSIZE   200
 #define USBASP_WRITEBLOCKSIZE  200
 
-/* ISP SCK speed identifiers */
+// ISP SCK speed identifiers
 #define USBASP_ISP_SCK_AUTO   0
-#define USBASP_ISP_SCK_0_5    1   /* 500 Hz */
-#define USBASP_ISP_SCK_1      2   /*   1 kHz */
-#define USBASP_ISP_SCK_2      3   /*   2 kHz */
-#define USBASP_ISP_SCK_4      4   /*   4 kHz */
-#define USBASP_ISP_SCK_8      5   /*   8 kHz */
-#define USBASP_ISP_SCK_16     6   /*  16 kHz */
-#define USBASP_ISP_SCK_32     7   /*  32 kHz */
-#define USBASP_ISP_SCK_93_75  8   /*  93.75 kHz */
-#define USBASP_ISP_SCK_187_5  9   /* 187.5  kHz */
-#define USBASP_ISP_SCK_375    10  /* 375 kHz   */
-#define USBASP_ISP_SCK_750    11  /* 750 kHz   */
-#define USBASP_ISP_SCK_1500   12  /* 1.5 MHz   */
-#define USBASP_ISP_SCK_3000   13  /*   3 MHz   only UsbAsp-flash firmware*/
+#define USBASP_ISP_SCK_0_5    1 // 500 Hz
+#define USBASP_ISP_SCK_1      2 //   1 kHz
+#define USBASP_ISP_SCK_2      3 //   2 kHz
+#define USBASP_ISP_SCK_4      4 //   4 kHz
+#define USBASP_ISP_SCK_8      5 //   8 kHz
+#define USBASP_ISP_SCK_16     6 //  16 kHz
+#define USBASP_ISP_SCK_32     7 //  32 kHz
+#define USBASP_ISP_SCK_93_75  8 //  93.75 kHz
+#define USBASP_ISP_SCK_187_5  9 // 187.5  kHz
+#define USBASP_ISP_SCK_375   10 // 375 kHz
+#define USBASP_ISP_SCK_750   11 // 750 kHz
+#define USBASP_ISP_SCK_1500  12 //   1.5 MHz
+#define USBASP_ISP_SCK_3000  13 //   3 MHz only UsbAsp-flash firmware
 
-/* TPI instructions */
+// TPI instructions
 #define TPI_OP_SLD      0x20
 #define TPI_OP_SLD_INC  0x24
 #define TPI_OP_SST      0x60
@@ -78,7 +78,7 @@
 #define TPI_OP_SSTCS(a) (0xC0 | ((a)&0x0F) )
 #define TPI_OP_SKEY     0xE0
 
-/* TPI control/status registers */
+// TPI control/status registers
 #define TPIIR  0xF
 #define TPIPCR 0x2
 #define TPISR  0x0
@@ -99,7 +99,7 @@
 // TPISR bits
 #define TPISR_NVMEN    0x02
 
-/* NVM registers */
+// NVM registers
 #define NVMCSR         0x32
 #define NVMCMD         0x33
 
@@ -112,13 +112,12 @@
 #define NVMCMD_SECTION_ERASE 0x14
 #define NVMCMD_WORD_WRITE    0x1D
 
-
 typedef struct sckoptions {
   int id;
   double frequency;
 } CLOCKOPTIONS;
 
-/* USB error identifiers */
+// USB error identifiers
 #define USB_ERROR_NOTFOUND  1
 #define USB_ERROR_ACCESS    2
 #define USB_ERROR_IO        3
@@ -127,11 +126,11 @@ typedef struct sckoptions {
 extern "C" {
 #endif
 
-extern const char usbasp_desc[];
-void usbasp_initpgm(PROGRAMMER *pgm);
+  extern const char usbasp_desc[];
+  void usbasp_initpgm(PROGRAMMER *pgm);
 
 #ifdef __cplusplus
 }
 #endif
 
-#endif /* usbasp_h */
+#endif