diff --git a/optipdf b/optipdf
index 3a63f3e..fc32636 100755
--- a/optipdf
+++ b/optipdf
@@ -105,22 +105,6 @@ if [[ ${#FILES[@]} -eq 0 ]]; then
     exit 2
 fi
 
-check_required_binaries() {
-    local BIN MISSING=()
-    for BIN; do
-        if ! type -t "$BIN" &>/dev/null; then
-            MISSING+=("$BIN")
-        fi
-    done
-    if [[ ${#MISSING[@]} -gt 0 ]]; then
-        printf 'Error: You are missing required programs:\n' >&2
-        for BIN in "${MISSING[@]}"; do
-            printf -- '- %s\n' "$BIN" >&2
-        done
-        exit 2
-    fi
-}
-
 file_size() {
     stat \
         --format='%s' \
@@ -132,10 +116,43 @@ file_size() {
 
 # produces a human-readable size from the byte count passed to it
 hr_size() (
-    numfmt \
-        --to=iec \
-        --suffix=B \
-        "$@"
+    declare -i BYTES=$1
+
+    #UNITS=(B KB MB GB TB PB EB ZB YB) # shell math can only go so far...
+    UNITS=(B KB MB GB TB)
+    FACT=1024
+    THRESH=9/10
+    DECIMALS=1
+    DECIMALS_FACTOR=$(( 10 ** DECIMALS ))
+
+    # cycle through units from largest to smallest, exiting when it finds the
+    # largest applicable unit
+    for (( EXP = ${#UNITS[@]} - 1; EXP > -1; --EXP )); do
+        # check if the unit is close enough to the unit's size, within the
+        # threshold
+        if [[ $BYTES -gt $((FACT ** EXP * $THRESH)) ]]; then
+            # we found the applicable unit
+
+            # must multiply by a factor of 10 here to not truncate
+            # the given number of decimal places after the point
+            HR_VAL=$(( BYTES * DECIMALS_FACTOR / FACT ** EXP ))
+
+            # put the decimal point in
+            if [[ $DECIMALS -gt 0 ]]; then
+                HR_VAL=$(( HR_VAL / DECIMALS_FACTOR )).$(( HR_VAL % DECIMALS_FACTOR ))
+            fi
+
+            HR_UNIT=${UNITS[$EXP]}
+            break
+        fi
+    done
+
+    if [[ -z $HR_UNIT ]]; then
+        HR_VAL=$BYTES
+        HR_UNIT=${UNITS[0]}
+    fi
+
+    printf '%g %s\n' "$HR_VAL" "$HR_UNIT"
 )
 
 setup_tempdir() {
@@ -216,9 +233,6 @@ use_smaller() {
 
 }
 
-check_required_binaries \
-    qpdf
-
 QPDF_ARGS=(
     --compression-level=9
     --deterministic-id