diff --git a/package.json b/package.json
index c404367..04738b8 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,7 @@
   "name": "grim",
   "version": "2.0.3",
   "description": "Log usage of deprecated methods",
-  "main": "./lib/grim",
+  "main": "./src/grim.js",
   "scripts": {
     "prepublish": "grunt clean lint coffee",
     "test": "grunt test"
diff --git a/src/deprecation.coffee b/src/deprecation.coffee
deleted file mode 100644
index 4fa4603..0000000
--- a/src/deprecation.coffee
+++ /dev/null
@@ -1,93 +0,0 @@
-SourceMapCache = {}
-
-module.exports =
-class Deprecation
-  @getFunctionNameFromCallsite: (callsite) ->
-
-  @deserialize: ({message, fileName, lineNumber, stacks}) ->
-    deprecation = new Deprecation(message, fileName, lineNumber)
-    deprecation.addStack(stack, stack.metadata) for stack in stacks
-    deprecation
-
-  constructor: (@message, @fileName, @lineNumber) ->
-    @callCount = 0
-    @stackCount = 0
-    @stacks = {}
-    @stackCallCounts = {}
-
-  getFunctionNameFromCallsite: (callsite) ->
-    return callsite.functionName if callsite.functionName?
-
-    if callsite.isToplevel()
-      callsite.getFunctionName() ? '<unknown>'
-    else
-      if callsite.isConstructor()
-        "new #{callsite.getFunctionName()}"
-      else if callsite.getMethodName() and not callsite.getFunctionName()
-        callsite.getMethodName()
-      else
-        "#{callsite.getTypeName()}.#{callsite.getMethodName() ? callsite.getFunctionName() ? '<anonymous>'}"
-
-  getLocationFromCallsite: (callsite) ->
-    return "unknown" unless callsite?
-    return callsite.location if callsite.location?
-
-    if callsite.isNative()
-      "native"
-    else if callsite.isEval()
-      "eval at #{@getLocationFromCallsite(callsite.getEvalOrigin())}"
-    else
-      fileName = callsite.getFileName()
-      line = callsite.getLineNumber()
-      column = callsite.getColumnNumber()
-      "#{fileName}:#{line}:#{column}"
-
-  getFileNameFromCallSite: (callsite) ->
-    callsite.fileName ? callsite.getFileName()
-
-  getOriginName: ->
-    @originName
-
-  getMessage: ->
-    @message
-
-  getStacks: ->
-    parsedStacks = []
-    for location, stack of @stacks
-      parsedStack = @parseStack(stack)
-      parsedStack.callCount = @stackCallCounts[location]
-      parsedStack.metadata = stack.metadata
-      parsedStacks.push(parsedStack)
-    parsedStacks
-
-  getStackCount: ->
-    @stackCount
-
-  getCallCount: ->
-    @callCount
-
-  addStack: (stack, metadata) ->
-    @originName ?= @getFunctionNameFromCallsite(stack[0])
-    @fileName ?= @getFileNameFromCallSite(stack[0])
-    @lineNumber ?= stack[0].getLineNumber?()
-    @callCount++
-
-    stack.metadata = metadata
-    callerLocation = @getLocationFromCallsite(stack[1])
-    unless @stacks[callerLocation]?
-      @stacks[callerLocation] = stack
-      @stackCount++
-    @stackCallCounts[callerLocation] ?= 0
-    @stackCallCounts[callerLocation]++
-
-  parseStack: (stack) ->
-    stack.map (callsite) =>
-      functionName: @getFunctionNameFromCallsite(callsite)
-      location: @getLocationFromCallsite(callsite)
-      fileName: @getFileNameFromCallSite(callsite)
-
-  serialize: ->
-    message: @getMessage()
-    lineNumber: @lineNumber
-    fileName: @fileName
-    stacks: @getStacks()
diff --git a/src/deprecation.js b/src/deprecation.js
index 32986eb..63539f3 100644
--- a/src/deprecation.js
+++ b/src/deprecation.js
@@ -1,16 +1,8 @@
-/*
- * decaffeinate suggestions:
- * DS101: Remove unnecessary use of Array.from
- * DS102: Remove unnecessary code created because of implicit returns
- * DS104: Avoid inline assignments
- * DS207: Consider shorter variations of null checks
- * Full docs: https://github.com/decaffeinate/decaffeinate/blob/main/docs/suggestions.md
- */
-let Deprecation;
+
 const SourceMapCache = {};
 
 module.exports =
-(Deprecation = class Deprecation {
+class Deprecation {
   static getFunctionNameFromCallsite(callsite) {}
 
   static deserialize({message, fileName, lineNumber, stacks}) {
@@ -33,16 +25,14 @@ module.exports =
     if (callsite.functionName != null) { return callsite.functionName; }
 
     if (callsite.isToplevel()) {
-      let left;
-      return (left = callsite.getFunctionName()) != null ? left : '<unknown>';
+      return callsite.getFunctionName() ?? "<unknown>";
     } else {
       if (callsite.isConstructor()) {
         return `new ${callsite.getFunctionName()}`;
       } else if (callsite.getMethodName() && !callsite.getFunctionName()) {
         return callsite.getMethodName();
       } else {
-        let left1, left2;
-        return `${callsite.getTypeName()}.${(left1 = (left2 = callsite.getMethodName()) != null ? left2 : callsite.getFunctionName()) != null ? left1 : '<anonymous>'}`;
+        return `${callsite.getTypeName()}.${callsite.getMethodName() ?? callsite.getFunctionName() ?? "<anonymous>" }`;
       }
     }
   }
@@ -129,4 +119,4 @@ module.exports =
       stacks: this.getStacks()
     };
   }
-});
+}
diff --git a/src/grim.coffee b/src/grim.coffee
deleted file mode 100644
index da3cf66..0000000
--- a/src/grim.coffee
+++ /dev/null
@@ -1,88 +0,0 @@
-Deprecation = require './deprecation'
-
-unless global.__grim__?
-  {Emitter} = require 'event-kit'
-  grim = global.__grim__ =
-    deprecations: {}
-    emitter: new Emitter
-    includeDeprecatedAPIs: true
-
-    getDeprecations: ->
-      deprecations = []
-      for fileName, deprecationsByLineNumber of grim.deprecations
-        for lineNumber, deprecationsByPackage of deprecationsByLineNumber
-          for packageName, deprecation of deprecationsByPackage
-            deprecations.push(deprecation)
-      deprecations
-
-    getDeprecationsLength: ->
-      @getDeprecations().length
-
-    clearDeprecations: ->
-      grim.deprecations = {}
-      return
-
-    logDeprecations: ->
-      deprecations = @getDeprecations()
-      deprecations.sort (a, b) -> b.getCallCount() - a.getCallCount()
-
-      console.warn "\nCalls to deprecated functions\n-----------------------------"
-      for deprecation in deprecations
-        console.warn "(#{deprecation.getCallCount()}) #{deprecation.getOriginName()} : #{deprecation.getMessage()}", deprecation
-      return
-
-    deprecate: (message, metadata) ->
-      # Capture a 5-deep stack trace
-      originalStackTraceLimit = Error.stackTraceLimit
-      try
-        Error.stackTraceLimit = 7
-        error = new Error
-        # Get an array of v8 CallSite objects
-        stack = error.getRawStack?() ? getRawStack(error)
-        stack = stack.slice(1)
-      finally
-        Error.stackTraceLimit = originalStackTraceLimit
-
-      # Find or create a deprecation for this site
-      deprecationSite = stack[0]
-      fileName = deprecationSite.getFileName()
-      lineNumber = deprecationSite.getLineNumber()
-      packageName = metadata?.packageName ? ""
-      grim.deprecations[fileName] ?= {}
-      grim.deprecations[fileName][lineNumber] ?= {}
-      grim.deprecations[fileName][lineNumber][packageName] ?= new Deprecation(message)
-
-      deprecation = grim.deprecations[fileName][lineNumber][packageName]
-
-      # Add the current stack trace to the deprecation
-      deprecation.addStack(stack, metadata)
-      grim.emitter.emit("updated", deprecation)
-      return
-
-    addSerializedDeprecation: (serializedDeprecation) ->
-      deprecation = Deprecation.deserialize(serializedDeprecation)
-      message = deprecation.getMessage()
-      {fileName, lineNumber} = deprecation
-      stacks = deprecation.getStacks()
-      packageName = stacks[0]?.metadata?.packageName ? ""
-
-      grim.deprecations[fileName] ?= {}
-      grim.deprecations[fileName][lineNumber] ?= {}
-      grim.deprecations[fileName][lineNumber][packageName] ?= new Deprecation(message, fileName, lineNumber)
-
-      deprecation = grim.deprecations[fileName][lineNumber][packageName]
-      deprecation.addStack(stack, stack.metadata) for stack in stacks
-      grim.emitter.emit("updated", deprecation)
-      return
-
-    on: (eventName, callback) -> grim.emitter.on(eventName, callback)
-
-getRawStack = (error) ->
-  originalPrepareStackTrace = Error.prepareStackTrace
-  Error.prepareStackTrace = (error, stack) -> stack
-  Error.captureStackTrace(error, getRawStack)
-  result = error.stack
-  Error.prepareStackTrace = originalPrepareStackTrace
-  result
-
-module.exports = global.__grim__
diff --git a/src/grim.js b/src/grim.js
index 515ec42..0171604 100644
--- a/src/grim.js
+++ b/src/grim.js
@@ -1,17 +1,8 @@
-/*
- * decaffeinate suggestions:
- * DS101: Remove unnecessary use of Array.from
- * DS102: Remove unnecessary code created because of implicit returns
- * DS103: Rewrite code to no longer use __guard__, or convert again using --optional-chaining
- * DS104: Avoid inline assignments
- * DS207: Consider shorter variations of null checks
- * Full docs: https://github.com/decaffeinate/decaffeinate/blob/main/docs/suggestions.md
- */
-const Deprecation = require('./deprecation');
+const Deprecation = require('./deprecation.js');
 
 if (global.__grim__ == null) {
-  const {Emitter} = require('event-kit');
-  var grim = (global.__grim__ = {
+  const { Emitter } = require('event-kit');
+  const grim = {
     deprecations: {},
     emitter: new Emitter,
     includeDeprecatedAPIs: true,
@@ -58,7 +49,7 @@ if (global.__grim__ == null) {
         Error.stackTraceLimit = 7;
         const error = new Error;
         // Get an array of v8 CallSite objects
-        stack = (left = (typeof error.getRawStack === 'function' ? error.getRawStack() : undefined)) != null ? left : getRawStack(error);
+        stack = error?.getRawStack?.() ?? getRawStack(error);
         stack = stack.slice(1);
       } finally {
         Error.stackTraceLimit = originalStackTraceLimit;
@@ -68,10 +59,12 @@ if (global.__grim__ == null) {
       const deprecationSite = stack[0];
       const fileName = deprecationSite.getFileName();
       const lineNumber = deprecationSite.getLineNumber();
-      const packageName = (metadata != null ? metadata.packageName : undefined) != null ? (metadata != null ? metadata.packageName : undefined) : "";
+      const packageName = metadata?.packageName ?? "";
       if (grim.deprecations[fileName] == null) { grim.deprecations[fileName] = {}; }
       if (grim.deprecations[fileName][lineNumber] == null) { grim.deprecations[fileName][lineNumber] = {}; }
-      if (grim.deprecations[fileName][lineNumber][packageName] == null) { grim.deprecations[fileName][lineNumber][packageName] = new Deprecation(message); }
+      if (grim.deprecations[fileName][lineNumber][packageName] == null) {
+        grim.deprecations[fileName][lineNumber][packageName] = new Deprecation(message);
+      }
 
       const deprecation = grim.deprecations[fileName][lineNumber][packageName];
 
@@ -85,11 +78,13 @@ if (global.__grim__ == null) {
       const message = deprecation.getMessage();
       const {fileName, lineNumber} = deprecation;
       const stacks = deprecation.getStacks();
-      const packageName = __guard__(stacks[0] != null ? stacks[0].metadata : undefined, x => x.packageName) != null ? __guard__(stacks[0] != null ? stacks[0].metadata : undefined, x => x.packageName) : "";
+      const packageName = stacks[0]?.metadata?.packageName ?? "";
 
       if (grim.deprecations[fileName] == null) { grim.deprecations[fileName] = {}; }
       if (grim.deprecations[fileName][lineNumber] == null) { grim.deprecations[fileName][lineNumber] = {}; }
-      if (grim.deprecations[fileName][lineNumber][packageName] == null) { grim.deprecations[fileName][lineNumber][packageName] = new Deprecation(message, fileName, lineNumber); }
+      if (grim.deprecations[fileName][lineNumber][packageName] == null) {
+        grim.deprecations[fileName][lineNumber][packageName] = new Deprecation(message, fileName, lineNumber);
+      }
 
       deprecation = grim.deprecations[fileName][lineNumber][packageName];
       for (let stack of Array.from(stacks)) { deprecation.addStack(stack, stack.metadata); }
@@ -97,20 +92,18 @@ if (global.__grim__ == null) {
     },
 
     on(eventName, callback) { return grim.emitter.on(eventName, callback); }
-  });
+  };
+
+  global.__grim__ = grim;
 }
 
-var getRawStack = function(error) {
+function getRawStack(error) {
   const originalPrepareStackTrace = Error.prepareStackTrace;
   Error.prepareStackTrace = (error, stack) => stack;
   Error.captureStackTrace(error, getRawStack);
   const result = error.stack;
   Error.prepareStackTrace = originalPrepareStackTrace;
   return result;
-};
+}
 
 module.exports = global.__grim__;
-
-function __guard__(value, transform) {
-  return (typeof value !== 'undefined' && value !== null) ? transform(value) : undefined;
-}