diff --git a/Cargo.lock b/Cargo.lock
index d5b7e61c9..37d2536bc 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1630,9 +1630,9 @@ checksum = "7ffc5c5338469d4d3ea17d269fa8ea3512ad247247c30bd2df69e68309ed0a08"
 
 [[package]]
 name = "mdbook"
-version = "0.4.8"
+version = "0.4.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fed4060ccf332a0479df37e84c8435ad20be737d5337c3a90fa1b3b0d480a3a0"
+checksum = "aeb86d199d0c1e8d41f3a9e9b0ba8639d6951a10043129159809ac9c18e3ce05"
 dependencies = [
  "ammonia",
  "anyhow",
diff --git a/cli/Cargo.toml b/cli/Cargo.toml
index 05cfcb20c..fca908f70 100644
--- a/cli/Cargo.toml
+++ b/cli/Cargo.toml
@@ -27,7 +27,7 @@ lazy_static = "1"
 iso8601-duration = "0.1"
 
 # only needed for usage-docs
-mdbook = { version = "0.4", optional = true }
+mdbook = { version = "0.4.9", optional = true }
 serde_json = { version = "*", optional = true }
 
 [dependencies.taskchampion]
diff --git a/cli/src/argparse/args/arg_matching.rs b/cli/src/argparse/args/arg_matching.rs
index e1161738e..f52aa4254 100644
--- a/cli/src/argparse/args/arg_matching.rs
+++ b/cli/src/argparse/args/arg_matching.rs
@@ -44,7 +44,7 @@ mod test {
     fn test_arg_matching() {
         assert_eq!(
             arg_matching(plus_tag)(argv!["+foo", "bar"]).unwrap(),
-            (argv!["bar"], "foo")
+            (argv!["bar"], tag!("foo"))
         );
         assert!(arg_matching(plus_tag)(argv!["foo", "bar"]).is_err());
     }
diff --git a/cli/src/argparse/args/misc.rs b/cli/src/argparse/args/misc.rs
index 006a0b939..27d2a1315 100644
--- a/cli/src/argparse/args/misc.rs
+++ b/cli/src/argparse/args/misc.rs
@@ -25,7 +25,7 @@ mod test {
     fn test_arg_matching() {
         assert_eq!(
             arg_matching(plus_tag)(argv!["+foo", "bar"]).unwrap(),
-            (argv!["bar"], "foo")
+            (argv!["bar"], tag!("foo"))
         );
         assert!(arg_matching(plus_tag)(argv!["foo", "bar"]).is_err());
     }
diff --git a/cli/src/argparse/args/tags.rs b/cli/src/argparse/args/tags.rs
index 8c2cbd9c1..c15dae6bf 100644
--- a/cli/src/argparse/args/tags.rs
+++ b/cli/src/argparse/args/tags.rs
@@ -3,31 +3,13 @@ use std::convert::TryFrom;
 use taskchampion::Tag;
 
 /// Recognizes a tag prefixed with `+` and returns the tag value
-pub(crate) fn plus_tag(input: &str) -> IResult<&str, &str> {
-    fn to_tag(input: (char, &str)) -> Result<&str, ()> {
-        Ok(input.1)
-    }
-    map_res(
-        all_consuming(tuple((
-            char('+'),
-            recognize(verify(rest, |s: &str| Tag::try_from(s).is_ok())),
-        ))),
-        to_tag,
-    )(input)
+pub(crate) fn plus_tag(input: &str) -> IResult<&str, Tag> {
+    preceded(char('+'), map_res(rest, Tag::try_from))(input)
 }
 
 /// Recognizes a tag prefixed with `-` and returns the tag value
-pub(crate) fn minus_tag(input: &str) -> IResult<&str, &str> {
-    fn to_tag(input: (char, &str)) -> Result<&str, ()> {
-        Ok(input.1)
-    }
-    map_res(
-        all_consuming(tuple((
-            char('-'),
-            recognize(verify(rest, |s: &str| Tag::try_from(s).is_ok())),
-        ))),
-        to_tag,
-    )(input)
+pub(crate) fn minus_tag(input: &str) -> IResult<&str, Tag> {
+    preceded(char('-'), map_res(rest, Tag::try_from))(input)
 }
 
 #[cfg(test)]
@@ -36,21 +18,17 @@ mod test {
 
     #[test]
     fn test_plus_tag() {
-        assert_eq!(plus_tag("+abc").unwrap().1, "abc");
-        assert_eq!(plus_tag("+abc123").unwrap().1, "abc123");
+        assert_eq!(plus_tag("+abc").unwrap().1, tag!("abc"));
+        assert_eq!(plus_tag("+abc123").unwrap().1, tag!("abc123"));
         assert!(plus_tag("-abc123").is_err());
-        assert!(plus_tag("+abc123  ").is_err());
-        assert!(plus_tag("  +abc123").is_err());
         assert!(plus_tag("+1abc").is_err());
     }
 
     #[test]
     fn test_minus_tag() {
-        assert_eq!(minus_tag("-abc").unwrap().1, "abc");
-        assert_eq!(minus_tag("-abc123").unwrap().1, "abc123");
+        assert_eq!(minus_tag("-abc").unwrap().1, tag!("abc"));
+        assert_eq!(minus_tag("-abc123").unwrap().1, tag!("abc123"));
         assert!(minus_tag("+abc123").is_err());
-        assert!(minus_tag("-abc123  ").is_err());
-        assert!(minus_tag("  -abc123").is_err());
         assert!(minus_tag("-1abc").is_err());
     }
 }
diff --git a/cli/src/argparse/filter.rs b/cli/src/argparse/filter.rs
index be63aa1af..fa2746bb1 100644
--- a/cli/src/argparse/filter.rs
+++ b/cli/src/argparse/filter.rs
@@ -8,7 +8,7 @@ use nom::{
     multi::{fold_many0, fold_many1},
     IResult,
 };
-use taskchampion::Status;
+use taskchampion::{Status, Tag};
 
 /// A filter represents a selection of a particular set of tasks.
 ///
@@ -26,10 +26,10 @@ pub(crate) struct Filter {
 #[derive(Debug, PartialEq, Clone)]
 pub(crate) enum Condition {
     /// Task has the given tag
-    HasTag(String),
+    HasTag(Tag),
 
     /// Task does not have the given tag
-    NoTag(String),
+    NoTag(Tag),
 
     /// Task has the given status
     Status(Status),
@@ -68,15 +68,15 @@ impl Condition {
     }
 
     fn parse_plus_tag(input: ArgList) -> IResult<ArgList, Condition> {
-        fn to_condition(input: &str) -> Result<Condition, ()> {
-            Ok(Condition::HasTag(input.to_owned()))
+        fn to_condition(input: Tag) -> Result<Condition, ()> {
+            Ok(Condition::HasTag(input))
         }
         map_res(arg_matching(plus_tag), to_condition)(input)
     }
 
     fn parse_minus_tag(input: ArgList) -> IResult<ArgList, Condition> {
-        fn to_condition(input: &str) -> Result<Condition, ()> {
-            Ok(Condition::NoTag(input.to_owned()))
+        fn to_condition(input: Tag) -> Result<Condition, ()> {
+            Ok(Condition::NoTag(input))
         }
         map_res(arg_matching(minus_tag), to_condition)(input)
     }
@@ -320,8 +320,8 @@ mod test {
             Filter {
                 conditions: vec![
                     Condition::IdList(vec![TaskId::WorkingSetId(1),]),
-                    Condition::HasTag("yes".into()),
-                    Condition::NoTag("no".into()),
+                    Condition::HasTag(tag!("yes")),
+                    Condition::NoTag(tag!("no")),
                 ],
             }
         );
@@ -353,10 +353,10 @@ mod test {
                 conditions: vec![
                     // from first filter
                     Condition::IdList(vec![TaskId::WorkingSetId(1), TaskId::WorkingSetId(2),]),
-                    Condition::HasTag("yes".into()),
+                    Condition::HasTag(tag!("yes")),
                     // from second filter
                     Condition::IdList(vec![TaskId::WorkingSetId(2), TaskId::WorkingSetId(3)]),
-                    Condition::HasTag("no".into()),
+                    Condition::HasTag(tag!("no")),
                 ],
             }
         );
@@ -373,9 +373,9 @@ mod test {
                 conditions: vec![
                     // from first filter
                     Condition::IdList(vec![TaskId::WorkingSetId(1), TaskId::WorkingSetId(2),]),
-                    Condition::HasTag("yes".into()),
+                    Condition::HasTag(tag!("yes")),
                     // from second filter
-                    Condition::HasTag("no".into()),
+                    Condition::HasTag(tag!("no")),
                 ],
             }
         );
@@ -390,8 +390,8 @@ mod test {
             both,
             Filter {
                 conditions: vec![
-                    Condition::HasTag("yes".into()),
-                    Condition::HasTag("no".into()),
+                    Condition::HasTag(tag!("yes")),
+                    Condition::HasTag(tag!("no")),
                 ],
             }
         );
diff --git a/cli/src/argparse/modification.rs b/cli/src/argparse/modification.rs
index 083f7fc8e..bd37db928 100644
--- a/cli/src/argparse/modification.rs
+++ b/cli/src/argparse/modification.rs
@@ -4,7 +4,7 @@ use crate::usage;
 use chrono::prelude::*;
 use nom::{branch::alt, combinator::*, multi::fold_many0, IResult};
 use std::collections::HashSet;
-use taskchampion::Status;
+use taskchampion::{Status, Tag};
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum DescriptionMod {
@@ -44,17 +44,17 @@ pub struct Modification {
     pub active: Option<bool>,
 
     /// Add tags
-    pub add_tags: HashSet<String>,
+    pub add_tags: HashSet<Tag>,
 
     /// Remove tags
-    pub remove_tags: HashSet<String>,
+    pub remove_tags: HashSet<Tag>,
 }
 
 /// A single argument that is part of a modification, used internally to this module
 enum ModArg<'a> {
     Description(&'a str),
-    PlusTag(&'a str),
-    MinusTag(&'a str),
+    PlusTag(Tag),
+    MinusTag(Tag),
     Wait(Option<DateTime<Utc>>),
 }
 
@@ -71,10 +71,10 @@ impl Modification {
                     }
                 }
                 ModArg::PlusTag(tag) => {
-                    acc.add_tags.insert(tag.to_owned());
+                    acc.add_tags.insert(tag);
                 }
                 ModArg::MinusTag(tag) => {
-                    acc.remove_tags.insert(tag.to_owned());
+                    acc.remove_tags.insert(tag);
                 }
                 ModArg::Wait(wait) => {
                     acc.wait = Some(wait);
@@ -105,14 +105,14 @@ impl Modification {
     }
 
     fn plus_tag(input: ArgList) -> IResult<ArgList, ModArg> {
-        fn to_modarg(input: &str) -> Result<ModArg, ()> {
+        fn to_modarg(input: Tag) -> Result<ModArg<'static>, ()> {
             Ok(ModArg::PlusTag(input))
         }
         map_res(arg_matching(plus_tag), to_modarg)(input)
     }
 
     fn minus_tag(input: ArgList) -> IResult<ArgList, ModArg> {
-        fn to_modarg(input: &str) -> Result<ModArg, ()> {
+        fn to_modarg(input: Tag) -> Result<ModArg<'static>, ()> {
             Ok(ModArg::MinusTag(input))
         }
         map_res(arg_matching(minus_tag), to_modarg)(input)
@@ -198,7 +198,7 @@ mod test {
         assert_eq!(
             modification,
             Modification {
-                add_tags: set![s!("abc"), s!("def")],
+                add_tags: set![tag!("abc"), tag!("def")],
                 ..Default::default()
             }
         );
@@ -252,8 +252,8 @@ mod test {
             modification,
             Modification {
                 description: DescriptionMod::Set(s!("new desc fun")),
-                add_tags: set![s!("next")],
-                remove_tags: set![s!("daytime")],
+                add_tags: set![tag!("next")],
+                remove_tags: set![tag!("daytime")],
                 ..Default::default()
             }
         );
diff --git a/cli/src/bin/usage-docs.rs b/cli/src/bin/usage-docs.rs
index f78179c71..baa4079e1 100644
--- a/cli/src/bin/usage-docs.rs
+++ b/cli/src/bin/usage-docs.rs
@@ -40,7 +40,10 @@ fn process(_ctx: &PreprocessorContext, mut book: Book) -> Result<Book, Error> {
             if new_content != chapter.content {
                 eprintln!(
                     "Substituting usage in {:?}",
-                    chapter.source_path.as_ref().unwrap()
+                    chapter
+                        .source_path
+                        .as_ref()
+                        .unwrap_or(chapter.path.as_ref().unwrap())
                 );
             }
             chapter.content = new_content;
diff --git a/cli/src/invocation/filter.rs b/cli/src/invocation/filter.rs
index 0cc6e31fe..0d4add799 100644
--- a/cli/src/invocation/filter.rs
+++ b/cli/src/invocation/filter.rs
@@ -1,22 +1,17 @@
 use crate::argparse::{Condition, Filter, TaskId};
 use std::collections::HashSet;
-use std::convert::TryInto;
-use taskchampion::{Replica, Status, Tag, Task, Uuid, WorkingSet};
+use taskchampion::{Replica, Status, Task, Uuid, WorkingSet};
 
 fn match_task(filter: &Filter, task: &Task, uuid: Uuid, working_set: &WorkingSet) -> bool {
     for cond in &filter.conditions {
         match cond {
             Condition::HasTag(ref tag) => {
-                // see #111 for the unwrap
-                let tag: Tag = tag.try_into().unwrap();
-                if !task.has_tag(&tag) {
+                if !task.has_tag(tag) {
                     return false;
                 }
             }
             Condition::NoTag(ref tag) => {
-                // see #111 for the unwrap
-                let tag: Tag = tag.try_into().unwrap();
-                if task.has_tag(&tag) {
+                if task.has_tag(tag) {
                     return false;
                 }
             }
@@ -254,8 +249,8 @@ mod test {
     #[test]
     fn tag_filtering() -> anyhow::Result<()> {
         let mut replica = test_replica();
-        let yes: Tag = "yes".try_into()?;
-        let no: Tag = "no".try_into()?;
+        let yes = tag!("yes");
+        let no = tag!("no");
 
         let mut t1 = replica
             .new_task(Status::Pending, s!("A"))?
@@ -274,7 +269,7 @@ mod test {
 
         // look for just "yes" (A and B)
         let filter = Filter {
-            conditions: vec![Condition::HasTag(s!("yes"))],
+            conditions: vec![Condition::HasTag(tag!("yes"))],
         };
         let mut filtered: Vec<_> = filtered_tasks(&mut replica, &filter)?
             .map(|t| t.get_description().to_owned())
@@ -284,7 +279,7 @@ mod test {
 
         // look for tags without "no" (A, D)
         let filter = Filter {
-            conditions: vec![Condition::NoTag(s!("no"))],
+            conditions: vec![Condition::NoTag(tag!("no"))],
         };
         let mut filtered: Vec<_> = filtered_tasks(&mut replica, &filter)?
             .map(|t| t.get_description().to_owned())
@@ -294,7 +289,10 @@ mod test {
 
         // look for tags with "yes" and "no" (B)
         let filter = Filter {
-            conditions: vec![Condition::HasTag(s!("yes")), Condition::HasTag(s!("no"))],
+            conditions: vec![
+                Condition::HasTag(tag!("yes")),
+                Condition::HasTag(tag!("no")),
+            ],
         };
         let filtered: Vec<_> = filtered_tasks(&mut replica, &filter)?
             .map(|t| t.get_description().to_owned())
diff --git a/cli/src/invocation/modify.rs b/cli/src/invocation/modify.rs
index 7ef6d758c..dd943fdd1 100644
--- a/cli/src/invocation/modify.rs
+++ b/cli/src/invocation/modify.rs
@@ -1,5 +1,4 @@
 use crate::argparse::{DescriptionMod, Modification};
-use std::convert::TryInto;
 use taskchampion::TaskMut;
 
 /// Apply the given modification
@@ -31,12 +30,10 @@ pub(super) fn apply_modification(
     }
 
     for tag in modification.add_tags.iter() {
-        let tag = tag.try_into()?; // see #111
         task.add_tag(&tag)?;
     }
 
     for tag in modification.remove_tags.iter() {
-        let tag = tag.try_into()?; // see #111
         task.remove_tag(&tag)?;
     }
 
diff --git a/cli/src/macros.rs b/cli/src/macros.rs
index 02e11e5cf..1a3024c13 100644
--- a/cli/src/macros.rs
+++ b/cli/src/macros.rs
@@ -30,3 +30,9 @@ macro_rules! set(
 macro_rules! s(
     { $s:expr } => { $s.to_owned() };
 );
+
+/// Create a Tag from an &str; just a testing shorthand
+#[cfg(test)]
+macro_rules! tag(
+    { $s:expr } => { { use std::convert::TryFrom; taskchampion::Tag::try_from($s).unwrap() } };
+);
diff --git a/cli/src/usage.rs b/cli/src/usage.rs
index 59a2ba982..b3f688909 100644
--- a/cli/src/usage.rs
+++ b/cli/src/usage.rs
@@ -93,7 +93,7 @@ impl Usage {
     /// With the appropriate documentation.
     pub fn substitute_docs(&self, content: &str) -> Result<String> {
         // this is not efficient, but it doesn't need to be
-        let mut lines = content.lines();
+        let lines = content.lines();
         let mut w = String::new();
 
         const DOC_HEADER_PREFIX: &str = "<!-- INSERT GENERATED DOCUMENTATION - ";