diff --git a/cmd_sorted_set.go b/cmd_sorted_set.go
index 86e4dfd..bc1afc0 100644
--- a/cmd_sorted_set.go
+++ b/cmd_sorted_set.go
@@ -838,7 +838,11 @@ func (m *Miniredis) makeCmdZrank(reverse bool) server.Cmd {
 			}
 
 			if !db.exists(key) {
-				c.WriteNull()
+				if withScore {
+					c.WriteLen(-1)
+				} else {
+					c.WriteNull()
+				}
 				return
 			}
 
@@ -853,7 +857,11 @@ func (m *Miniredis) makeCmdZrank(reverse bool) server.Cmd {
 			}
 			rank, ok := db.ssetRank(key, member, direction)
 			if !ok {
-				c.WriteNull()
+				if withScore {
+					c.WriteLen(-1)
+				} else {
+					c.WriteNull()
+				}
 				return
 			}
 
@@ -864,8 +872,6 @@ func (m *Miniredis) makeCmdZrank(reverse bool) server.Cmd {
 			} else {
 				c.WriteInt(rank)
 			}
-
-			
 		})
 	}
 }
diff --git a/integration/sorted_set_test.go b/integration/sorted_set_test.go
index 79ff45b..72b9abf 100644
--- a/integration/sorted_set_test.go
+++ b/integration/sorted_set_test.go
@@ -18,13 +18,18 @@ func TestSortedSet(t *testing.T) {
 		c.Do("ZRANK", "z", "mies")
 		c.Do("ZRANK", "z", "vuur")
 		c.Do("ZRANK", "z", "nosuch")
+		c.Do("ZRANK", "z", "vuur", "WITHSCORE")
 		c.Do("ZRANK", "nosuch", "nosuch")
+		c.Do("ZRANK", "z", "nosuch", "WITHSCORE")
+		c.Do("ZRANK", "nosuch", "nosuch", "WITHSCORE")
 		c.Do("ZREVRANK", "z", "aap")
 		c.Do("ZREVRANK", "z", "noot")
 		c.Do("ZREVRANK", "z", "mies")
 		c.Do("ZREVRANK", "z", "vuur")
 		c.Do("ZREVRANK", "z", "nosuch")
 		c.Do("ZREVRANK", "nosuch", "nosuch")
+		c.Do("ZREVRANK", "z", "noot", "WITHSCORE")
+		c.Do("ZREVRANK", "nosuch", "nosuch", "WITHSCORE")
 
 		c.Do("ZADD", "zi", "inf", "aap", "-inf", "noot", "+inf", "mies")
 		c.Do("ZRANK", "zi", "noot")
@@ -70,6 +75,8 @@ func TestSortedSet(t *testing.T) {
 		c.Error("wrong number", "ZPOPMIN")
 		c.Error("out of range", "ZPOPMIN", "set", "noint")
 		c.Error("syntax error", "ZPOPMIN", "set", "1", "toomany")
+		c.Error("syntax error", "ZRANK", "z", "nosuch", "WITHSCORES")
+		c.Error("syntax error", "ZREVRANK", "z", "nosuch", "WITHSCORES")
 
 		c.Do("RENAME", "z", "z2")
 		c.Do("EXISTS", "z")