diff --git a/src/commands.rs b/src/commands.rs
index 48eaa0e..a8da19c 100644
--- a/src/commands.rs
+++ b/src/commands.rs
@@ -1,12 +1,23 @@
 use crate::cofd::dice::DicePool;
 use crate::context::Context;
+use crate::db::DataError;
 use crate::dice::ElementExpression;
-use crate::error::{BotError, CommandError};
+use crate::error::BotError;
 use crate::help::HelpTopic;
 use crate::roll::Roll;
+use thiserror::Error;
 
 pub mod parser;
 
+#[derive(Error, Debug)]
+pub enum CommandError {
+    #[error("invalid command: {0}")]
+    InvalidCommand(String),
+
+    #[error("ignored command")]
+    IgnoredCommand,
+}
+
 pub struct Execution {
     plain: String,
     html: String,
@@ -104,8 +115,8 @@ impl Command for GetVariableCommand {
     fn execute(&self, ctx: &Context) -> Execution {
         let name = &self.0;
         let value = match ctx.db.get_user_variable(ctx.room_id, ctx.username, name) {
-            Ok(Some(num)) => format!("{} = {}", name, num),
-            Ok(None) => format!("{} is not set", name),
+            Ok(num) => format!("{} = {}", name, num),
+            Err(DataError::KeyDoesNotExist(_)) => format!("{} is not set", name),
             Err(e) => format!("error getting {}: {}", name, e),
         };
 
@@ -125,16 +136,17 @@ impl Command for SetVariableCommand {
     fn execute(&self, ctx: &Context) -> Execution {
         let name = &self.0;
         let value = self.1;
-        let value = match ctx
+        let result = ctx
             .db
-            .set_user_variable(ctx.room_id, ctx.username, name, value)
-        {
+            .set_user_variable(ctx.room_id, ctx.username, name, value);
+
+        let content = match result {
             Ok(_) => format!("{} = {}", name, value),
             Err(e) => format!("error setting {}: {}", name, e),
         };
 
-        let plain = format!("Set Variable: {}", value);
-        let html = format!("<p><strong>Set Variable:</strong> {}", value);
+        let plain = format!("Set Variable: {}", content);
+        let html = format!("<p><strong>Set Variable:</strong> {}", content);
         Execution { plain, html }
     }
 }
@@ -150,6 +162,7 @@ impl Command for DeleteVariableCommand {
         let name = &self.0;
         let value = match ctx.db.delete_user_variable(ctx.room_id, ctx.username, name) {
             Ok(()) => format!("{} now unset", name),
+            Err(DataError::KeyDoesNotExist(_)) => format!("{} is not currently set", name),
             Err(e) => format!("error deleting {}: {}", name, e),
         };
 
diff --git a/src/config.rs b/src/config.rs
index e3e58e5..1590813 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -1,8 +1,17 @@
-use crate::error::ConfigError;
 use serde::{self, Deserialize, Serialize};
 use std::env;
 use std::fs;
 use std::path::PathBuf;
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+pub enum ConfigError {
+    #[error("i/o error: {0}")]
+    IoError(#[from] std::io::Error),
+
+    #[error("toml parsing error: {0}")]
+    TomlParsingError(#[from] toml::de::Error),
+}
 
 pub fn read_config<P: Into<PathBuf>>(config_path: P) -> Result<Config, ConfigError> {
     let config_path = config_path.into();
diff --git a/src/db.rs b/src/db.rs
index 1cae17b..14b998f 100644
--- a/src/db.rs
+++ b/src/db.rs
@@ -36,17 +36,17 @@ impl Database {
         room_id: &str,
         username: &str,
         variable_name: &str,
-    ) -> Result<Option<i32>, DataError> {
+    ) -> Result<i32, DataError> {
         let key = to_key(room_id, username, variable_name);
 
-        if let Some(raw_value) = self.db.get(key)? {
+        if let Some(raw_value) = self.db.get(&key)? {
             let layout: LayoutVerified<&[u8], I32<LittleEndian>> =
                 LayoutVerified::new_unaligned(&*raw_value).expect("bytes do not fit schema");
 
             let value: I32<LittleEndian> = *layout;
-            Ok(Some(value.get()))
+            Ok(value.get())
         } else {
-            Ok(None)
+            Err(DataError::KeyDoesNotExist(String::from_utf8(key).unwrap()))
         }
     }
 
@@ -59,7 +59,7 @@ impl Database {
     ) -> Result<(), DataError> {
         let key = to_key(room_id, username, variable_name);
         let db_value: I32<LittleEndian> = I32::new(value);
-        self.db.insert(key, IVec::from(db_value.as_bytes()))?;
+        self.db.insert(&key, IVec::from(db_value.as_bytes()))?;
         Ok(())
     }
 
@@ -70,13 +70,10 @@ impl Database {
         variable_name: &str,
     ) -> Result<(), DataError> {
         let key = to_key(room_id, username, variable_name);
-        if let Some(_) = self.db.remove(key)? {
+        if let Some(_) = self.db.remove(&key)? {
             Ok(())
         } else {
-            let mut key = room_id.to_owned();
-            key.push_str(username);
-            key.push_str(variable_name);
-            Err(DataError::KeyDoesNotExist(key))
+            Err(DataError::KeyDoesNotExist(String::from_utf8(key).unwrap()))
         }
     }
 }
diff --git a/src/error.rs b/src/error.rs
index cf1beb8..fa34ac5 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -1,24 +1,8 @@
+use crate::commands::CommandError;
+use crate::config::ConfigError;
 use crate::db::DataError;
 use thiserror::Error;
 
-#[derive(Error, Debug)]
-pub enum ConfigError {
-    #[error("i/o error: {0}")]
-    IoError(#[from] std::io::Error),
-
-    #[error("toml parsing error: {0}")]
-    TomlParsingError(#[from] toml::de::Error),
-}
-
-#[derive(Error, Debug)]
-pub enum CommandError {
-    #[error("invalid command: {0}")]
-    InvalidCommand(String),
-
-    #[error("ignored command")]
-    IgnoredCommand,
-}
-
 #[derive(Error, Debug)]
 pub enum BotError {
     #[error("configuration error: {0}")]