diff --git a/bin/pt-mysql-summary b/bin/pt-mysql-summary
index eb506ff6..7356cd14 100755
--- a/bin/pt-mysql-summary
+++ b/bin/pt-mysql-summary
@@ -576,22 +576,19 @@ shorten() {
    local div="${3:-1024}"
 
    echo "$num" | awk -v prec="$prec" -v div="$div" '
-   {
-      size = 4;
-      val  = $1;
-
-      unit = val >= 1099511627776 ? "T" : val >= 1073741824 ? "G" : val >= 1048576 ? "M" : val >= 1024 ? "k" : "";
-
-      while ( int(val) && !(val % 1024) ) {
-         val /= 1024;
+      {
+         num  = $1;
+         unit = num >= 1125899906842624 ? "P" \
+              : num >= 1099511627776    ? "T" \
+              : num >= 1073741824       ? "G" \
+              : num >= 1048576          ? "M" \
+              : num >= 1024             ? "k" \
+              :                           "";
+         while ( num >= div ) {
+            num /= div;
+         }
+         printf "%.*f%s", prec, num, unit;
       }
-
-      while ( val > 1000 ) {
-         val /= div;
-      }
-
-      printf "%.*f%s", prec, val, unit;
-   }
    '
 }
 
diff --git a/bin/pt-summary b/bin/pt-summary
index 63bac1ae..23152e0c 100755
--- a/bin/pt-summary
+++ b/bin/pt-summary
@@ -713,22 +713,19 @@ shorten() {
    local div="${3:-1024}"
 
    echo "$num" | awk -v prec="$prec" -v div="$div" '
-   {
-      num = $1;
-
-      unit = num >= 1125899906842624 ? "P" \
-           : num >= 1099511627776    ? "T" \
-           : num >= 1073741824       ? "G" \
-           : num >= 1048576          ? "M" \
-           : num >= 1024             ? "k" \
-           :                           "";
-
-      while ( num >= div ) {
-         num /= div;
+      {
+         num  = $1;
+         unit = num >= 1125899906842624 ? "P" \
+              : num >= 1099511627776    ? "T" \
+              : num >= 1073741824       ? "G" \
+              : num >= 1048576          ? "M" \
+              : num >= 1024             ? "k" \
+              :                           "";
+         while ( num >= div ) {
+            num /= div;
+         }
+         printf "%.*f%s", prec, num, unit;
       }
-
-      printf "%.*f%s", prec, num, unit;
-   }
    '
 }
 
diff --git a/lib/bash/report_formatting.sh b/lib/bash/report_formatting.sh
index 8542ece6..76386317 100644
--- a/lib/bash/report_formatting.sh
+++ b/lib/bash/report_formatting.sh
@@ -87,23 +87,29 @@ shorten() {
    local prec="${2:-2}"
    local div="${3:-1024}"
 
+   # By default Mebibytes (MiB), Gigibytes (GiB), etc. are used because
+   # that's what MySQL uses.  This may create odd output for values like
+   # 1500M * 2 (bug 937793) because the base unit is MiB but the code
+   # see 1,572,864,000 * 2 = 3,145,728,000 which is > 1 GiB so it uses
+   # GiB as the unit, resulting in 2.9G instead of 3.0G that the user
+   # might expect to see.  There's no easy way to determine that
+   # 3,145,728,000 was actually a multiple of MiB and not some weird GiB
+   # value to begin with like 3.145G.  The Perl lib Transformers::shorten()
+   # uses MiB, GiB, etc. too.
    echo "$num" | awk -v prec="$prec" -v div="$div" '
-   {
-      num = $1;
-
-      unit = num >= 1125899906842624 ? "P" \
-           : num >= 1099511627776    ? "T" \
-           : num >= 1073741824       ? "G" \
-           : num >= 1048576          ? "M" \
-           : num >= 1024             ? "k" \
-           :                           "";
-
-      while ( num >= div ) {
-         num /= div;
+      {
+         num  = $1;
+         unit = num >= 1125899906842624 ? "P" \
+              : num >= 1099511627776    ? "T" \
+              : num >= 1073741824       ? "G" \
+              : num >= 1048576          ? "M" \
+              : num >= 1024             ? "k" \
+              :                           "";
+         while ( num >= div ) {
+            num /= div;
+         }
+         printf "%.*f%s", prec, num, unit;
       }
-
-      printf "%.*f%s", prec, num, unit;
-   }
    '
 }
 
diff --git a/t/lib/bash/report_formatting.sh b/t/lib/bash/report_formatting.sh
index 8974646d..373371a7 100644
--- a/t/lib/bash/report_formatting.sh
+++ b/t/lib/bash/report_formatting.sh
@@ -78,7 +78,7 @@ is \
 is \
    "$(section "A_B_C")" \
    "# A#B#C#######################################################" \
-   "replace everything after and including first underscore with #s"
+   "replace extra underscores with #s"
 
 # name_val