diff --git a/src/lexer.rs b/src/lexer.rs
index 11a9e89..51ad6a5 100644
--- a/src/lexer.rs
+++ b/src/lexer.rs
@@ -41,7 +41,7 @@ pub fn lex(input: &str) -> Result<TokenVector, String> {
       '\'' => tokens.push(Token::Unit(Foot)),
       '"' | '“' | '”' | '″' => tokens.push(Token::LexerKeyword(DoubleQuotes)),
       value if value.is_whitespace() => {},
-      value if value.is_alphabetic() => {
+      value if value.is_ascii_alphabetic() => {
 
         let start_index = byte_index;
         let mut end_index = byte_index;
@@ -52,7 +52,7 @@ pub fn lex(input: &str) -> Result<TokenVector, String> {
             return Err(format!("Invalid string starting with: {}", string));
           }
 
-          if current_char.is_alphabetic() {
+          if current_char.is_ascii_alphabetic() {
             byte_index += current_char.len_utf8();
             chars.next();
             end_index += 1;
diff --git a/src/main.rs b/src/main.rs
index 6e65173..2ebb2d4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -88,12 +88,13 @@ mod evaluator;
 mod lookup;
 
 fn main() {
-  let lex_start = Instant::now();
   
   use std::env;
   let args: Vec<String> = env::args().collect();
   let s = if args.len() >= 2 { &args[1] } else { "0.1" };
 
+  let lex_start = Instant::now();
+  
   match lexer::lex(s) {
     Ok(tokens) => {
       let lex_time = Instant::now().duration_since(lex_start).as_nanos() as f32;
diff --git a/src/units.rs b/src/units.rs
index 1ce9e85..ec287d0 100644
--- a/src/units.rs
+++ b/src/units.rs
@@ -71,6 +71,7 @@ create_units!(
   Foot:               (Length, d128!(304.8)),
   Yard:               (Length, d128!(914.4)),
   Mile:               (Length, d128!(1609344)),
+  // 1-dimensional only:
   NauticalMile:       (Length, d128!(1852000)),
   LightYear:          (Length, d128!(9460730472580800000)),
   LightSecond:        (Length, d128!(299792458000)),
@@ -84,6 +85,7 @@ create_units!(
   SquareFoot:         (Area, d128!(92903.04)),
   SquareYard:         (Area, d128!(836127.36)),
   SquareMile:         (Area, d128!(2589988110336.00)),
+  // 2-dimensional only
   Are:                (Area, d128!(100000000)),
   Decare:             (Area, d128!(1000000000)),
   Hectare:            (Area, d128!(10000000000)),
@@ -98,6 +100,7 @@ create_units!(
   CubicFoot:          (Volume, d128!(28316846.592)),
   CubicYard:          (Volume, d128!(764554857.984)),
   CubicMile:          (Volume, d128!(4168181825440579584)),
+  // 3-dimensional only
   Milliliter:         (Volume, d128!(1000)),
   Centiliter:         (Volume, d128!(10000)),
   Deciliter:          (Volume, d128!(100000)),