diff --git a/lib/thor/actions/file_manipulation.rb b/lib/thor/actions/file_manipulation.rb
index 3c5f16d35..8eec045e1 100644
--- a/lib/thor/actions/file_manipulation.rb
+++ b/lib/thor/actions/file_manipulation.rb
@@ -274,9 +274,8 @@ def gsub_file(path, flag, *args, &block)
       end
     end
 
-    # Uncomment all lines matching a given regex.  It will leave the space
-    # which existed before the comment hash in tact but will remove any spacing
-    # between the comment hash and the beginning of the line.
+    # Uncomment all lines matching a given regex. Preserves indentation before
+    # the comment hash and removes the hash and any immediate following space.
     #
     # ==== Parameters
     # path<String>:: path of the file to be changed
@@ -290,7 +289,7 @@ def gsub_file(path, flag, *args, &block)
     def uncomment_lines(path, flag, *args)
       flag = flag.respond_to?(:source) ? flag.source : flag
 
-      gsub_file(path, /^(\s*)#[[:blank:]]*(.*#{flag})/, '\1\2', *args)
+      gsub_file(path, /^(\s*)#[[:blank:]]?(.*#{flag})/, '\1\2', *args)
     end
 
     # Comment all lines matching a given regex.  It will leave the space
diff --git a/spec/actions/file_manipulation_spec.rb b/spec/actions/file_manipulation_spec.rb
index a1b902af3..72919e09b 100644
--- a/spec/actions/file_manipulation_spec.rb
+++ b/spec/actions/file_manipulation_spec.rb
@@ -475,20 +475,26 @@ def file
       File.join(destination_root, "doc", "COMMENTER")
     end
 
-    unmodified_comments_file = /__start__\n # greenblue\n#\n# yellowblue\n#yellowred\n #greenred\norange\n    purple\n  ind#igo\n  # ind#igo\n__end__/
+    unmodified_comments_file = /__start__\n # greenblue\n#\n# yellowblue\n#yellowred\n #greenred\norange\n    purple\n  ind#igo\n  # ind#igo\n  #   spaces_between\n__end__/
 
     describe "#uncomment_lines" do
       it "uncomments all matching lines in the file" do
         action :uncomment_lines, "doc/COMMENTER", "green"
-        expect(File.binread(file)).to match(/__start__\n greenblue\n#\n# yellowblue\n#yellowred\n greenred\norange\n    purple\n  ind#igo\n  # ind#igo\n__end__/)
+        expect(File.binread(file)).to match(/__start__\n greenblue\n#\n# yellowblue\n#yellowred\n greenred\norange\n    purple\n  ind#igo\n  # ind#igo\n  #   spaces_between\n__end__/)
 
         action :uncomment_lines, "doc/COMMENTER", "red"
-        expect(File.binread(file)).to match(/__start__\n greenblue\n#\n# yellowblue\nyellowred\n greenred\norange\n    purple\n  ind#igo\n  # ind#igo\n__end__/)
+        expect(File.binread(file)).to match(/__start__\n greenblue\n#\n# yellowblue\nyellowred\n greenred\norange\n    purple\n  ind#igo\n  # ind#igo\n  #   spaces_between\n__end__/)
       end
 
       it "correctly uncomments lines with hashes in them" do
         action :uncomment_lines, "doc/COMMENTER", "ind#igo"
-        expect(File.binread(file)).to match(/__start__\n # greenblue\n#\n# yellowblue\n#yellowred\n #greenred\norange\n    purple\n  ind#igo\n  ind#igo\n__end__/)
+        expect(File.binread(file)).to match(/__start__\n # greenblue\n#\n# yellowblue\n#yellowred\n #greenred\norange\n    purple\n  ind#igo\n  ind#igo\n  #   spaces_between\n__end__/)
+      end
+
+      it "will leave the space which existed before the comment hash in tact" do
+        action :uncomment_lines, "doc/COMMENTER", "ind#igo"
+        action :uncomment_lines, "doc/COMMENTER", "spaces_between"
+        expect(File.binread(file)).to match(/__start__\n # greenblue\n#\n# yellowblue\n#yellowred\n #greenred\norange\n    purple\n  ind#igo\n  ind#igo\n    spaces_between\n__end__/)
       end
 
       it "does not modify already uncommented lines in the file" do
@@ -499,22 +505,22 @@ def file
 
       it "does not uncomment the wrong line when uncommenting lines preceded by blank commented line" do
         action :uncomment_lines, "doc/COMMENTER", "yellow"
-        expect(File.binread(file)).to match(/__start__\n # greenblue\n#\nyellowblue\nyellowred\n #greenred\norange\n    purple\n  ind#igo\n  # ind#igo\n__end__/)
+        expect(File.binread(file)).to match(/__start__\n # greenblue\n#\nyellowblue\nyellowred\n #greenred\norange\n    purple\n  ind#igo\n  # ind#igo\n  #   spaces_between\n__end__/)
       end
     end
 
     describe "#comment_lines" do
       it "comments lines which are not commented" do
         action :comment_lines, "doc/COMMENTER", "orange"
-        expect(File.binread(file)).to match(/__start__\n # greenblue\n#\n# yellowblue\n#yellowred\n #greenred\n# orange\n    purple\n  ind#igo\n  # ind#igo\n__end__/)
+        expect(File.binread(file)).to match(/__start__\n # greenblue\n#\n# yellowblue\n#yellowred\n #greenred\n# orange\n    purple\n  ind#igo\n  # ind#igo\n  #   spaces_between\n__end__/)
 
         action :comment_lines, "doc/COMMENTER", "purple"
-        expect(File.binread(file)).to match(/__start__\n # greenblue\n#\n# yellowblue\n#yellowred\n #greenred\n# orange\n    # purple\n  ind#igo\n  # ind#igo\n__end__/)
+        expect(File.binread(file)).to match(/__start__\n # greenblue\n#\n# yellowblue\n#yellowred\n #greenred\n# orange\n    # purple\n  ind#igo\n  # ind#igo\n  #   spaces_between\n__end__/)
       end
 
       it "correctly comments lines with hashes in them" do
         action :comment_lines, "doc/COMMENTER", "ind#igo"
-        expect(File.binread(file)).to match(/__start__\n # greenblue\n#\n# yellowblue\n#yellowred\n #greenred\norange\n    purple\n  # ind#igo\n  # ind#igo\n__end__/)
+        expect(File.binread(file)).to match(/__start__\n # greenblue\n#\n# yellowblue\n#yellowred\n #greenred\norange\n    purple\n  # ind#igo\n  # ind#igo\n  #   spaces_between\n__end__/)
       end
 
       it "does not modify already commented lines" do
diff --git a/spec/fixtures/doc/COMMENTER b/spec/fixtures/doc/COMMENTER
index 384cb3a50..84e62144a 100644
--- a/spec/fixtures/doc/COMMENTER
+++ b/spec/fixtures/doc/COMMENTER
@@ -8,4 +8,5 @@ orange
     purple
   ind#igo
   # ind#igo
+  #   spaces_between
 __end__