diff --git a/x/mongo/driver/connstring/connstring.go b/x/mongo/driver/connstring/connstring.go
index f5f8631b57..25869ef425 100644
--- a/x/mongo/driver/connstring/connstring.go
+++ b/x/mongo/driver/connstring/connstring.go
@@ -746,7 +746,9 @@ func (p *parser) addOption(pair string) error {
 		p.ReadPreference = value
 	case "readpreferencetags":
 		if value == "" {
-			// for when readPreferenceTags= at end of URI
+			// If "readPreferenceTags=" is supplied, append an empty map to tag sets to
+			// represent a wild-card.
+			p.ReadPreferenceTagSets = append(p.ReadPreferenceTagSets, map[string]string{})
 			break
 		}
 
diff --git a/x/mongo/driver/connstring/connstring_test.go b/x/mongo/driver/connstring/connstring_test.go
index b051c7e588..c5eccdc077 100644
--- a/x/mongo/driver/connstring/connstring_test.go
+++ b/x/mongo/driver/connstring/connstring_test.go
@@ -382,8 +382,8 @@ func TestReadPreferenceTags(t *testing.T) {
 		{s: "readPreferenceTags=one:1,two:2", expected: []map[string]string{{"one": "1", "two": "2"}}},
 		{s: "readPreferenceTags=one:1&readPreferenceTags=two:2", expected: []map[string]string{{"one": "1"}, {"two": "2"}}},
 		{s: "readPreferenceTags=one:1:3,two:2", err: true},
-		{s: "readPreferenceTags=one:1&readPreferenceTags=two:2&readPreferenceTags=", expected: []map[string]string{{"one": "1"}, {"two": "2"}}},
-		{s: "readPreferenceTags=", expected: nil},
+		{s: "readPreferenceTags=one:1&readPreferenceTags=two:2&readPreferenceTags=", expected: []map[string]string{{"one": "1"}, {"two": "2"}, {}}},
+		{s: "readPreferenceTags=", expected: []map[string]string{{}}},
 	}
 
 	for _, test := range tests {