diff --git a/src/avrdude.conf.in b/src/avrdude.conf.in
index 3eec6197..e87fcea8 100644
--- a/src/avrdude.conf.in
+++ b/src/avrdude.conf.in
@@ -1236,7 +1236,7 @@ programmer # ft232h_jtag
 # Pin J2-10 (AD3) is RESET
 # Pin J2-6 is GND
 # Use the -b flag to set the SPI clock rate eg -b 3750000 is the fastest I could get
-# a 16MHz Atmega1280 to program reliably.  The 232H is conveniently 5V tolerant.
+# a 16 MHz Atmega1280 to program reliably.  The 232H is conveniently 5 V tolerant.
 
 programmer parent "ft232h" # um232h
     id                     = "um232h";
@@ -1254,7 +1254,7 @@ programmer parent "ft232h" # um232h
 # Brown (Pin 5) is RESET
 # Black (Pin 10) is GND
 # Use the -b flag to set the SPI clock rate eg -b 3750000 is the fastest I could get
-# a 16MHz Atmega1280 to program reliably.  The 232H is conveniently 5V tolerant.
+# a 16 MHz Atmega1280 to program reliably.  The 232H is conveniently 5 V tolerant.
 
 programmer parent "um232h" # c232hm
     id                     = "c232hm";
diff --git a/src/avrftdi.c b/src/avrftdi.c
index 2cf90cf9..7b85e340 100644
--- a/src/avrftdi.c
+++ b/src/avrftdi.c
@@ -798,7 +798,7 @@ static int avrftdi_initialize(const PROGRAMMER *pgm, const AVRPART *p) {
     // Use speed optimization with CAUTION
     usleep(20*1000);
 
-    // Giving rst-pulse of at least 2 avr-clock-cycles, for security (2us @ 1MHz)
+    // Giving rst-pulse of at least 2 avr-clock-cycles, for security (2 us @ 1 MHz)
     set_pin(pgm, PIN_AVR_RESET, ON);
     usleep(20*1000);
 
diff --git a/src/bitbang.c b/src/bitbang.c
index 4fdbb7f9..cef636c9 100644
--- a/src/bitbang.c
+++ b/src/bitbang.c
@@ -156,8 +156,8 @@ static unsigned char bitbang_txrx(const PROGRAMMER *pgm, unsigned char byte) {
      * if and only if T>t_CLCL (t_CLCL=clock period of target system).
      *
      * Due to the delay introduced by "IN" and "OUT"-commands, T is greater
-     * than 1us (more like 2us) on x86-architectures. So programming works
-     * safely down to 1MHz target clock.
+     * than 1us (more like 2 us) on x86-architectures. So programming works
+     * safely down to 1 MHz target clock.
      */
 
     b = (byte >> i) & 0x01;
diff --git a/src/buspirate.c b/src/buspirate.c
index c4bf5f0a..071a2af5 100644
--- a/src/buspirate.c
+++ b/src/buspirate.c
@@ -568,7 +568,7 @@ static int buspirate_start_mode_bin(PROGRAMMER *pgm) {
     unsigned short pwm_duty;
     unsigned short pwm_period;
 
-    pwm_period = 16000/(my.cpufreq) - 1; // Oscillator runs at 32MHz, we don't use a prescaler
+    pwm_period = 16000/(my.cpufreq) - 1; // Oscillator runs at 32 MHz, we don't use a prescaler
     pwm_duty = pwm_period/2;  // 50% duty cycle
 
     msg_notice2("setting up PWM for cpufreq\n");
diff --git a/src/ft245r.c b/src/ft245r.c
index 674b2c0a..41d75726 100644
--- a/src/ft245r.c
+++ b/src/ft245r.c
@@ -113,12 +113,12 @@ void ft245r_initpgm(PROGRAMMER *pgm) {
 
 /*
  * Some revisions of the FTDI chips mess up the timing in bitbang mode unless
- * the bitclock is set to the max (3MHz).  For example, see:
+ * the bitclock is set to the max (3 MHz).  For example, see:
  *
  * http://www.ftdichip.com/Support/Documents/TechnicalNotes/TN_120_FT232R%20Errata%20Technical%20Note.pdf
  *
  * To work around this problem, set the macro below to 1 to always set the
- * bitclock to 3MHz and then issue the same byte repeatedly to get the desired
+ * bitclock to 3 MHz and then issue the same byte repeatedly to get the desired
  * timing.
  *
 */
@@ -364,7 +364,7 @@ static int ft245r_set_bitclock(const PROGRAMMER *pgm) {
   } else if(pgm->baudrate) {
     rate = pgm->baudrate;
   } else {
-    rate = 150000;              // Should work for all ftdi chips and the avr default internal clock of 1MHz
+    rate = 150000;              // Should work for all ftdi chips and the internal clock of 1 MHz
   }
 
 #if FT245R_BITBANG_VARIABLE_PULSE_WIDTH_WORKAROUND
diff --git a/src/pickit2.c b/src/pickit2.c
index e4bc1963..8c66342c 100644
--- a/src/pickit2.c
+++ b/src/pickit2.c
@@ -1011,7 +1011,7 @@ static int pickit2_parseextparams(const PROGRAMMER *pgm, const LISTID extparms)
 
       int clock_period = MIN(1000000/clock_rate, 255);        // Max period is 255
 
-      clock_rate = (int) (1000000/(clock_period + 5e-7));     // Assume highest speed is 2MHz
+      clock_rate = (int) (1000000/(clock_period + 5e-7));     // Assume highest speed is 2 MHz
 
       pmsg_notice2("%s(): effective clock rate set to 0x%02x\n", __func__, clock_rate);
       my.clock_period = clock_period;
diff --git a/src/xbee.c b/src/xbee.c
index 75f8a330..a0591dee 100644
--- a/src/xbee.c
+++ b/src/xbee.c
@@ -1045,13 +1045,13 @@ static int xbeedev_open(const char *port, union pinfo pinfo, union filedescripto
      * In this mode, we are NOT talking to an XBee, we are talking directly to
      * an AVR device that thinks it is talking to an XBee itself.
      *
-     * Because, an XBee is a 3.3V device defaulting to 9600baud, and the
-     * Atmel328P is only rated at a maximum clock rate of 8MHz with a 3.3V
+     * Because, an XBee is a 3.3V device defaulting to 9600 baud, and the
+     * Atmel328P is only rated at a maximum clock rate of 8 MHz with a 3.3 V
      * supply, so there's a high likelihood a remote Atmel328P will be clocked
-     * at 8MHz.
+     * at 8 MHz.
      *
      * With a direct connection, there's a good chance we're talking to an
-     * Arduino clocked at 16MHz with an XBee-enabled chip plugged in.  The
+     * Arduino clocked at 16 MHz with an XBee-enabled chip plugged in.  The
      * doubled clock rate means a doubled serial rate.  Double 9600 baud ==
      * 19200 baud.
      */