diff --git a/app/logical/post_query/parser.rb b/app/logical/post_query/parser.rb
index 165a9ba37..2068f8724 100644
--- a/app/logical/post_query/parser.rb
+++ b/app/logical/post_query/parser.rb
@@ -172,7 +172,7 @@ class PostQuery
           expect("'")
           [true, a]
         else
-          [false, string(/[^ ]+/)]
+          [false, string(/[^ ]*/)]
         end
       end
 
diff --git a/test/unit/post_query_builder_test.rb b/test/unit/post_query_builder_test.rb
index e5327a92b..ef78ac6a6 100644
--- a/test/unit/post_query_builder_test.rb
+++ b/test/unit/post_query_builder_test.rb
@@ -896,6 +896,7 @@ class PostQueryBuilderTest < ActiveSupport::TestCase
       assert_tag_match([post3], "source:NONE")
       assert_tag_match([post3], 'source:""')
       assert_tag_match([post3], "source:''")
+      assert_tag_match([post3], "source:")
       assert_tag_match([post2, post1], "-source:none")
       assert_tag_match([post2, post1], "-source:''")
       assert_tag_match([post2, post1], '-source:""')
diff --git a/test/unit/post_query_parser_test.rb b/test/unit/post_query_parser_test.rb
index 72a325c38..92f5d599f 100644
--- a/test/unit/post_query_parser_test.rb
+++ b/test/unit/post_query_parser_test.rb
@@ -114,6 +114,7 @@ class PostQueryParserTest < ActiveSupport::TestCase
 
       assert_parse_equals('source:"foo bar"', 'source:"foo bar"')
       assert_parse_equals('source:foobar"(', 'source:foobar"(')
+      assert_parse_equals('source:', 'source:')
       assert_parse_equals('source:""', 'source:""')
       assert_parse_equals('source:"\""', 'source:"\""')
       assert_parse_equals(%q{source:"don't say \"lazy\" okay"}, %q{source:"don't say \"lazy\" okay"})