diff -ur avrdude.cvs/usbasp.c avrdude.new/usbasp.c
--- avrdude.cvs/usbasp.c	2007-11-07 22:36:12.000000000 +0200
+++ avrdude.new/usbasp.c	2008-03-29 22:32:26.000000000 +0200
@@ -227,7 +227,51 @@
 {
 
   unsigned char temp[4];
+  double clock = pgm->bitclock*1e+6;
+  double freq = 0; 
   memset(temp, 0, sizeof(temp));
+  
+  /* set ISP SCK speed index */
+  if (clock > 1500.0) { 
+    temp[0] = ISP_SCK_0_5;
+    freq = 0.5;
+  } else if (clock > 750.0) {
+    temp[0] = ISP_SCK_1;
+    freq = 1;  
+  } else if (clock > 375.0) {
+    temp[0] = ISP_SCK_2;
+    freq = 2;
+  } else if (clock > 187.5) { 
+    temp[0] = ISP_SCK_4;
+    freq = 4;
+  } else if (clock > 93.75) {
+    temp[0] = ISP_SCK_8;
+    freq = 8;
+  } else if (clock > 46.88) {
+    temp[0] = ISP_SCK_16;
+    freq = 16;
+  } else if (clock > 20.96) {
+    temp[0] = ISP_SCK_32;
+    freq = 32;
+  } else if (clock > 8.0) {
+    temp[0] = ISP_SCK_93_75;
+    freq = 93.75;
+  } else if (clock > 4.0) {
+    temp[0] = ISP_SCK_187_5;
+    freq = 187.5;
+  } else if (clock > 2.0) {
+    temp[0] = ISP_SCK_375;
+    freq = 375;
+  } else if (clock > 1.0) {
+    temp[0] = ISP_SCK_750;
+    freq = 750;
+  } else if (clock > 0.5) {
+    temp[0] = ISP_SCK_1500;
+    freq = 1500;
+  }
+  if (freq > 0) 
+    fprintf(stderr, "%s: USBasp: using %g kHz SCK\n", progname, freq);
+    
   usbasp_transmit(pgm, 1, USBASP_FUNC_CONNECT, temp, temp, sizeof(temp));
 
   usleep(100000);
diff -ur avrdude.cvs/usbasp.h avrdude.new/usbasp.h
--- avrdude.cvs/usbasp.h	2007-07-24 19:43:25.000000000 +0300
+++ avrdude.new/usbasp.h	2008-03-29 22:24:34.000000000 +0200
@@ -51,6 +51,23 @@
 #define USB_ERROR_ACCESS    2
 #define USB_ERROR_IO        3
 
+/* ISP SCK speed indexes */
+/* software ISP modes */
+#define ISP_SCK_0_5    23  /*   500 Hz */
+#define ISP_SCK_1      24  /*   1 kHz */
+#define ISP_SCK_2      25  /*   2 kHz */
+#define ISP_SCK_4      26  /*   4 kHz */
+#define ISP_SCK_8      27  /*   8 kHz */
+#define ISP_SCK_16     28  /*  16 kHz */
+#define ISP_SCK_32     29  /*  32 kHz */
+/* hardware ISP modes */		       
+#define ISP_SCK_93_75  30  /*  93.75 kHz */
+#define ISP_SCK_187_5  31  /* 187.5  kHz */
+#define ISP_SCK_375    32  /* 375 kHz   */
+#define ISP_SCK_750    33  /* 750 kHz   */
+#define ISP_SCK_1500   34  /* 1.5 MHz   */
+
+
 #ifdef __cplusplus
 extern "C" {
 #endif