diff --git a/src/coffee-script.coffee b/src/coffee-script.coffee
index 2d32c01e..e70e5a11 100644
--- a/src/coffee-script.coffee
+++ b/src/coffee-script.coffee
@@ -30,7 +30,7 @@ lexer = new Lexer
 # Compile a string of CoffeeScript code to JavaScript, using the Coffee/Jison
 # compiler.
 exports.compile = compile = (code, options) ->
-  options or= {}
+  options = or {}
   try
     (parser.parse lexer.tokenize code).compile options
   catch err
diff --git a/src/command.coffee b/src/command.coffee
index c4e7217a..4cd396e7 100644
--- a/src/command.coffee
+++ b/src/command.coffee
@@ -156,7 +156,7 @@ printTokens = (tokens) ->
 parseOptions = ->
   optionParser    = new optparse.OptionParser SWITCHES, BANNER
   o = options     = optionParser.parse(process.argv[2...process.argv.length])
-  options.compile or=  !!o.output
+  options.compile = or  !!o.output
   options.run     = not (o.compile or o.print or o.lint)
   options.print   = !!  (o.print or (o.eval or o.stdio and o.compile))
   sources         = options.arguments
diff --git a/src/lexer.coffee b/src/lexer.coffee
index e8f3eaa9..45704b92 100644
--- a/src/lexer.coffee
+++ b/src/lexer.coffee
@@ -259,7 +259,7 @@ exports.Lexer = class Lexer
     value = match and match[1]
     space = match and match[2]
     @tagParameters() if value and value.match CODE
-    value or= @chunk.substr 0, 1
+    value = or @chunk.substr 0, 1
     @i += value.length
     prevSpaced = @prev() and @prev().spaced
     tag = value
@@ -347,7 +347,7 @@ exports.Lexer = class Lexer
   # contents of the string. This method allows us to have strings within
   # interpolations within strings, ad infinitum.
   balancedString: (str, delimited, options) ->
-    options or= {}
+    options = or {}
     slash = delimited[0][0] is '/'
     levels = []
     i = 0
@@ -384,7 +384,7 @@ exports.Lexer = class Lexer
   # new Lexer, tokenize the interpolated contents, and merge them into the
   # token stream.
   interpolateString: (str, options) ->
-    options or= {}
+    options = or {}
     if str.length < 3 or not starts str, '"'
       @token 'STRING', str
     else
diff --git a/src/nodes.coffee b/src/nodes.coffee
index f1b56ca9..a4888167 100644
--- a/src/nodes.coffee
+++ b/src/nodes.coffee
@@ -112,7 +112,7 @@ exports.BaseNode = class BaseNode
   # `toString` representation of the node, for inspecting the parse tree.
   # This is what `coffee --nodes` prints out.
   toString: (idt, override) ->
-    idt or= ''
+    idt = or ''
     children = (child.toString idt + TAB for child in @collectChildren()).join('')
     '\n' + idt + (override or @class) + children
 
@@ -187,7 +187,7 @@ exports.Expressions = class Expressions extends BaseNode
 
   # An **Expressions** is the only node that can serve as the root.
   compile: (o) ->
-    o or= {}
+    o = or {}
     if o.scope then super(o) else @compileRoot(o)
 
   compileNode: (o) ->
@@ -348,7 +348,7 @@ exports.ValueNode = class ValueNode extends BaseNode
     only        = del o, 'onlyFirst'
     op          = del o, 'operation'
     props       = if only then @properties[0...@properties.length - 1] else @properties
-    o.chainRoot or= this
+    o.chainRoot = or this
     baseline    = @base.compile o
     baseline    = "(#baseline)" if @hasProperties() and (@base instanceof ObjectNode or @isNumber())
     complete    = @last = baseline
@@ -496,7 +496,7 @@ exports.AccessorNode = class AccessorNode extends BaseNode
 
   compileNode: (o) ->
     name = @name.compile o
-    o.chainRoot.wrapped or= @soakNode
+    o.chainRoot.wrapped = or @soakNode
     namePart = if name.match(IS_STRING) then "[#name]" else ".#name"
     @prototype + namePart
 
@@ -512,7 +512,7 @@ exports.IndexNode = class IndexNode extends BaseNode
     @index = index
 
   compileNode: (o) ->
-    o.chainRoot.wrapped or= @soakNode
+    o.chainRoot.wrapped = or @soakNode
     idx = @index.compile o
     prefix = if @proto then '.prototype' else ''
     "#prefix[#idx]"
@@ -564,7 +564,7 @@ exports.RangeNode = class RangeNode extends BaseNode
     [from, to] = [parseInt(@fromNum, 10), parseInt(@toNum, 10)]
     idx        = del o, 'index'
     step       = del o, 'step'
-    step       and= "#idx += #{step.compile(o)}"
+    step       = and "#idx += #{step.compile(o)}"
     if from <= to
       "#idx = #from; #idx <#@equals #to; #{step or "#idx++"}"
     else
@@ -715,8 +715,8 @@ exports.ClassNode = class ClassNode extends BaseNode
         continue
       if func instanceof CodeNode and func.bound
         func.bound = false
-        constScope or= new Scope(o.scope, constructor.body, constructor)
-        me or= constScope.freeVariable()
+        constScope = or new Scope(o.scope, constructor.body, constructor)
+        me = or constScope.freeVariable()
         pname = pvar.compile(o)
         constructor.body.push    new ReturnNode literal 'this' if constructor.body.empty()
         constructor.body.unshift literal "this.#{pname} = function(){ return #{className}.prototype.#{pname}.apply(#me, arguments); }"
@@ -897,7 +897,7 @@ exports.CodeNode = class CodeNode extends BaseNode
   traverseChildren: (crossScope, func) -> super(crossScope, func) if crossScope
 
   toString: (idt) ->
-    idt or= ''
+    idt = or ''
     children = (child.toString(idt + TAB) for child in @collectChildren()).join('')
     "\n#idt#children"
 
@@ -1382,7 +1382,7 @@ exports.IfNode = class IfNode extends BaseNode
   # The **IfNode** only compiles into a statement if either of its bodies needs
   # to be a statement. Otherwise a ternary is safe.
   isStatement: ->
-    @statement or= !!(@tags.statement or @bodyNode().isStatement() or (@elseBody and @elseBodyNode().isStatement()))
+    @statement = or !!(@tags.statement or @bodyNode().isStatement() or (@elseBody and @elseBodyNode().isStatement()))
 
   compileCondition: (o) ->
     (cond.compile(o) for cond in flatten([@condition])).join(' || ')
@@ -1392,8 +1392,8 @@ exports.IfNode = class IfNode extends BaseNode
 
   makeReturn: ->
     if @isStatement()
-      @body     and= @ensureExpressions(@body.makeReturn())
-      @elseBody and= @ensureExpressions(@elseBody.makeReturn())
+      @body     = and @ensureExpressions(@body.makeReturn())
+      @elseBody = and @ensureExpressions(@elseBody.makeReturn())
       this
     else
       new ReturnNode this
diff --git a/src/rewriter.coffee b/src/rewriter.coffee
index bc639f18..57a497b2 100644
--- a/src/rewriter.coffee
+++ b/src/rewriter.coffee
@@ -237,7 +237,7 @@ exports.Rewriter = class Rewriter
     @scanTokens (prev, token, post, i) =>
       for pair in pairs
         [open, close] = pair
-        levels[open] or= 0
+        levels[open] = or 0
         if token[0] is open
           openLine[open] = token[2] if levels[open] == 0
           levels[open] += 1
diff --git a/test/test_operations.coffee b/test/test_operations.coffee
index 364cf8b3..d857347e 100644
--- a/test/test_operations.coffee
+++ b/test/test_operations.coffee
@@ -69,13 +69,13 @@ ok x*+y is -50
 # Half-operators.
 one = two = null
 one = or 1
-two or=  2
+two = or  2
 
 ok one is 1
 ok two is 2
 
 one = and 'one'
-two and=  'two'
+two = and  'two'
 
 ok one is 'one'
 ok two is 'two'