diff --git a/lib/regexp-fields.cc b/lib/regexp-fields.cc
index 9dcf9732..1651677c 100644
--- a/lib/regexp-fields.cc
+++ b/lib/regexp-fields.cc
@@ -148,6 +148,11 @@ RegexpFieldProcessor::RegexpFieldProcessor (std::string prefix, Xapian::QueryPar
 Xapian::Query
 RegexpFieldProcessor::operator() (const std::string & str)
 {
+    if (str.size () == 0)
+	return Xapian::Query(Xapian::Query::OP_AND_NOT,
+			     Xapian::Query::MatchAll,
+			     Xapian::Query (Xapian::Query::OP_WILDCARD, term_prefix));
+
     if (str.at (0) == '/') {
 	if (str.at (str.size () - 1) == '/'){
 	    RegexpPostingSource *postings = new RegexpPostingSource (slot, str.substr(1,str.size () - 2));
diff --git a/test/T650-regexp-query.sh b/test/T650-regexp-query.sh
index f2ae1387..9599c104 100755
--- a/test/T650-regexp-query.sh
+++ b/test/T650-regexp-query.sh
@@ -16,7 +16,6 @@ add_message '[from]="-" [subject]="empty from"'
 add_message '[subject]="-"'
 
 test_begin_subtest "null from: search"
-test_subtest_known_broken
 notmuch search 'from:""' | notmuch_search_sanitize > OUTPUT
 cat <<EOF > EXPECTED
 thread:XXX   2001-01-05 [1/1] -; empty from (inbox unread)
@@ -24,7 +23,6 @@ EOF
 test_expect_equal_file EXPECTED OUTPUT
 
 test_begin_subtest "null subject: search"
-test_subtest_known_broken
 notmuch search 'subject:""' | notmuch_search_sanitize > OUTPUT
 cat <<EOF > EXPECTED
 thread:XXX   2001-01-05 [1/1] Notmuch Test Suite; - (inbox unread)