diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7b49269..bff4b5e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,6 @@
 ## HEAD (unreleased)
 
-- Replace some references in tests with foobar style code (https://github.com/zombocom/dead_end/pull/38)
+- Fix bug where empty lines were interpreted to have a zero indentation (https://github.com/zombocom/dead_end/pull/39)
 
 ## 1.0.1
 
diff --git a/lib/dead_end/code_block.rb b/lib/dead_end/code_block.rb
index 786fb9f..ee7df64 100644
--- a/lib/dead_end/code_block.rb
+++ b/lib/dead_end/code_block.rb
@@ -17,10 +17,12 @@ module DeadEnd
   #
   #
   class CodeBlock
+    UNSET = Object.new.freeze
     attr_reader :lines
 
     def initialize(lines: [])
       @lines = Array(lines)
+      @valid = UNSET
     end
 
     def visible_lines
@@ -68,7 +70,8 @@ def invalid?
     end
 
     def valid?
-      DeadEnd.valid?(self.to_s)
+      return @valid if @valid != UNSET
+      @valid = DeadEnd.valid?(self.to_s)
     end
 
     def to_s
diff --git a/lib/dead_end/code_frontier.rb b/lib/dead_end/code_frontier.rb
index 1ba6291..4634159 100644
--- a/lib/dead_end/code_frontier.rb
+++ b/lib/dead_end/code_frontier.rb
@@ -10,20 +10,20 @@ module DeadEnd
   # sorted and then the frontier can be filtered. Large blocks that totally contain a
   # smaller block will cause the smaller block to be evicted.
   #
-  #   CodeFrontier#<<
-  #   CodeFrontier#pop
+  #   CodeFrontier#<<(block) # Adds block to frontier
+  #   CodeFrontier#pop # Removes block from frontier
   #
   # ## Knowing where we can go
   #
-  # Internally it keeps track of an "indent hash" which is exposed via `next_indent_line`
+  # Internally it keeps track of "unvisited" lines which is exposed via `next_indent_line`
   # when called this will return a line of code with the most indentation.
   #
-  # This line of code can be used to build a CodeBlock via and then when that code block
-  # is added back to the frontier, then the lines in the code block are removed from the
-  # indent hash so we don't double-create the same block.
+  # This line of code can be used to build a CodeBlock and then when that code block
+  # is added back to the frontier, then the lines are removed from the
+  # "unvisited" so we don't double-create the same block.
   #
-  #   CodeFrontier#next_indent_line
-  #   CodeFrontier#register_indent_block
+  #   CodeFrontier#next_indent_line # Shows next line
+  #   CodeFrontier#register_indent_block(block) # Removes lines from unvisited
   #
   # ## Knowing when to stop
   #
@@ -42,13 +42,7 @@ class CodeFrontier
     def initialize(code_lines: )
       @code_lines = code_lines
       @frontier = []
-      @indent_hash = {}
-      code_lines.each do |line|
-        next if line.empty?
-
-        @indent_hash[line.indent] ||= []
-        @indent_hash[line.indent] << line
-      end
+      @unvisited_lines = @code_lines.sort_by(&:indent_index)
     end
 
     def count
@@ -75,38 +69,31 @@ def pop
       return @frontier.pop
     end
 
-    def indent_hash_indent
-      @indent_hash.keys.sort.last
-    end
-
     def next_indent_line
-      indent = @indent_hash.keys.sort.last
-      @indent_hash[indent]&.first
+      @unvisited_lines.last
     end
 
     def expand?
       return false if @frontier.empty?
-      return true if @indent_hash.empty?
+      return true if @unvisited_lines.empty?
 
       frontier_indent = @frontier.last.current_indent
-      hash_indent = @indent_hash.keys.sort.last
+      unvisited_indent= next_indent_line.indent
 
       if ENV["DEBUG"]
         puts "```"
         puts @frontier.last.to_s
         puts "```"
         puts "  @frontier indent: #{frontier_indent}"
-        puts "  @hash indent:     #{hash_indent}"
+        puts "  @unvisited indent:     #{unvisited_indent}"
       end
 
-      frontier_indent >= hash_indent
+      # Expand all blocks before moving to unvisited lines
+      frontier_indent >= unvisited_indent
     end
 
     def register_indent_block(block)
-      block.lines.each do |line|
-        @indent_hash[line.indent]&.delete(line)
-      end
-      @indent_hash.select! {|k, v| !v.empty?}
+      @unvisited_lines -= block.lines
       self
     end
 
diff --git a/lib/dead_end/code_line.rb b/lib/dead_end/code_line.rb
index 5c874b7..86148f7 100644
--- a/lib/dead_end/code_line.rb
+++ b/lib/dead_end/code_line.rb
@@ -36,9 +36,14 @@ class CodeLine
     def initialize(line: , index:)
       @original_line = line.freeze
       @line = @original_line
-      @empty = line.strip.empty?
+      if line.strip.empty?
+        @empty = true
+        @indent = 0
+      else
+        @empty = false
+        @indent = SpaceCount.indent(line)
+      end
       @index = index
-      @indent = SpaceCount.indent(line)
       @status = nil # valid, invalid, unknown
       @invalid = false
 
@@ -72,6 +77,10 @@ def trailing_slash?
       @is_trailing_slash
     end
 
+    def indent_index
+      @indent_index ||= [indent, index]
+    end
+
     def <=>(b)
       self.index <=> b.index
     end
@@ -92,15 +101,6 @@ def is_end?
       @is_end
     end
 
-    def mark_invalid
-      @invalid = true
-      self
-    end
-
-    def marked_invalid?
-      @invalid
-    end
-
     def mark_invisible
       @line = ""
       self
diff --git a/lib/dead_end/code_search.rb b/lib/dead_end/code_search.rb
index 7fc97e1..8c357b7 100644
--- a/lib/dead_end/code_search.rb
+++ b/lib/dead_end/code_search.rb
@@ -75,7 +75,7 @@ def push(block, name: )
       record(block: block, name: name)
 
       if block.valid?
-        block.lines.each(&:mark_invisible)
+        block.mark_invisible
         frontier << block
       else
         frontier << block
@@ -92,7 +92,7 @@ def sweep(block:, name: )
 
     # Parses the most indented lines into blocks that are marked
     # and added to the frontier
-    def add_invalid_blocks
+    def visit_new_blocks
       max_indent = frontier.next_indent_line&.indent
 
       while (line = frontier.next_indent_line) && (line.indent == max_indent)
@@ -145,7 +145,7 @@ def call
         if frontier.expand?
           expand_invalid_block
         else
-          add_invalid_blocks
+          visit_new_blocks
         end
       end
 
diff --git a/spec/unit/code_line_spec.rb b/spec/unit/code_line_spec.rb
index 1ba22f3..92e7bd5 100644
--- a/spec/unit/code_line_spec.rb
+++ b/spec/unit/code_line_spec.rb
@@ -41,20 +41,6 @@ module DeadEnd
       expect(line.is_kw?).to be_truthy
     end
 
-    it  "can be marked as invalid or valid" do
-      code_lines = code_line_array(<<~EOM)
-        def foo
-          Array(value) |x|
-          end
-        end
-      EOM
-
-      expect(code_lines[0].marked_invalid?).to be_falsey
-      code_lines[0].mark_invalid
-      expect(code_lines[0].marked_invalid?).to be_truthy
-
-    end
-
     it "ignores marked lines" do
       code_lines = code_line_array(<<~EOM)
         def foo
@@ -110,5 +96,14 @@ def foo
 
       expect(code_lines.map(&:indent)).to eq([0, 2, 4, 2, 0])
     end
+
+    it "doesn't count empty lines as having an indentation" do
+      code_lines = code_line_array(<<~EOM)
+
+
+      EOM
+
+      expect(code_lines.map(&:indent)).to eq([0, 0])
+    end
   end
 end
diff --git a/spec/unit/code_search_spec.rb b/spec/unit/code_search_spec.rb
index 6e1fac1..9fec231 100644
--- a/spec/unit/code_search_spec.rb
+++ b/spec/unit/code_search_spec.rb
@@ -277,7 +277,7 @@ def foo
 
         it "stacked ends 2" do
           search = CodeSearch.new(<<~EOM)
-            def lol
+            def cat
               blerg
             end
 
@@ -285,7 +285,7 @@ def lol
             end # one
             end # two
 
-            def lol
+            def dog
             end
           EOM
           search.call
@@ -445,7 +445,7 @@ def foo
           puts 'lol'
         end
       EOM
-      search.add_invalid_blocks
+      search.visit_new_blocks
 
       expect(search.code_lines.join).to eq(<<~EOM)
         def foo