diff --git a/schulze.go b/schulze.go
index 4467051..3bc3bba 100644
--- a/schulze.go
+++ b/schulze.go
@@ -24,9 +24,22 @@ func NewPreferences(choicesLength int) []int {
 // have the same rank. Ranks do not have to be in consecutive order.
 type Ballot[C comparable] map[C]int
 
-// Vote updates the preferences passed as th first argument with the Ballot
+// Vote updates the preferences passed as the first argument with the Ballot
 // values.
 func Vote[C comparable](preferences []int, choices []C, b Ballot[C]) error {
+	return vote(preferences, choices, b, 1) // add one to increment every pairwise preference
+}
+
+// Unvote removes the Ballot values from the preferences.
+func Unvote[C comparable](preferences []int, choices []C, b Ballot[C]) error {
+	return vote(preferences, choices, b, -1) // subtract one to decrement every pairwise preference
+}
+
+// vote updates the preferences with ballot values according to the passed
+// choices. The weight is the value which is added to the preferences slice
+// values for pairwise wins. If the weight is 1, the ballot is added, and if it
+// is -1 the ballot is removed.
+func vote[C comparable](preferences []int, choices []C, b Ballot[C], weight int) error {
 	ranks, choicesCount, err := ballotRanks(choices, b)
 	if err != nil {
 		return fmt.Errorf("ballot ranks: %w", err)
@@ -37,7 +50,7 @@ func Vote[C comparable](preferences []int, choices []C, b Ballot[C]) error {
 		for _, i := range choices1 {
 			for _, choices1 := range rest {
 				for _, j := range choices1 {
-					preferences[int(i)*choicesCount+int(j)]++
+					preferences[int(i)*choicesCount+int(j)] += weight
 				}
 			}
 		}
diff --git a/schulze_test.go b/schulze_test.go
index b298dcf..142b98f 100644
--- a/schulze_test.go
+++ b/schulze_test.go
@@ -16,10 +16,14 @@ import (
 )
 
 func TestVoting(t *testing.T) {
+	type ballot[C comparable] struct {
+		ballot schulze.Ballot[C]
+		unvote bool
+	}
 	for _, tc := range []struct {
 		name    string
 		choices []string
-		ballots []schulze.Ballot[string]
+		ballots []ballot[string]
 		result  []schulze.Result[string]
 		tie     bool
 	}{
@@ -37,8 +41,8 @@ func TestVoting(t *testing.T) {
 		{
 			name:    "single option one vote",
 			choices: []string{"A"},
-			ballots: []schulze.Ballot[string]{
-				{"A": 1},
+			ballots: []ballot[string]{
+				{ballot: schulze.Ballot[string]{"A": 1}},
 			},
 			result: []schulze.Result[string]{
 				{Choice: "A", Index: 0, Wins: 0},
@@ -47,8 +51,8 @@ func TestVoting(t *testing.T) {
 		{
 			name:    "two options one vote",
 			choices: []string{"A", "B"},
-			ballots: []schulze.Ballot[string]{
-				{"A": 1},
+			ballots: []ballot[string]{
+				{ballot: schulze.Ballot[string]{"A": 1}},
 			},
 			result: []schulze.Result[string]{
 				{Choice: "A", Index: 0, Wins: 1},
@@ -58,9 +62,9 @@ func TestVoting(t *testing.T) {
 		{
 			name:    "two options two votes",
 			choices: []string{"A", "B"},
-			ballots: []schulze.Ballot[string]{
-				{"A": 1},
-				{"A": 1, "B": 2},
+			ballots: []ballot[string]{
+				{ballot: schulze.Ballot[string]{"A": 1}},
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 2}},
 			},
 			result: []schulze.Result[string]{
 				{Choice: "A", Index: 0, Wins: 1},
@@ -70,10 +74,10 @@ func TestVoting(t *testing.T) {
 		{
 			name:    "three options three votes",
 			choices: []string{"A", "B", "C"},
-			ballots: []schulze.Ballot[string]{
-				{"A": 1},
-				{"A": 1, "B": 2},
-				{"A": 1, "B": 2, "C": 3},
+			ballots: []ballot[string]{
+				{ballot: schulze.Ballot[string]{"A": 1}},
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 2}},
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 2, "C": 3}},
 			},
 			result: []schulze.Result[string]{
 				{Choice: "A", Index: 0, Wins: 2},
@@ -84,9 +88,9 @@ func TestVoting(t *testing.T) {
 		{
 			name:    "tie",
 			choices: []string{"A", "B", "C"},
-			ballots: []schulze.Ballot[string]{
-				{"A": 1},
-				{"B": 1},
+			ballots: []ballot[string]{
+				{ballot: schulze.Ballot[string]{"A": 1}},
+				{ballot: schulze.Ballot[string]{"B": 1}},
 			},
 			result: []schulze.Result[string]{
 				{Choice: "A", Index: 0, Wins: 1},
@@ -98,11 +102,11 @@ func TestVoting(t *testing.T) {
 		{
 			name:    "complex",
 			choices: []string{"A", "B", "C", "D", "E"},
-			ballots: []schulze.Ballot[string]{
-				{"A": 1, "B": 1},
-				{"B": 1, "C": 1, "A": 2},
-				{"A": 1, "B": 2, "C": 2},
-				{"A": 1, "B": 200, "C": 10},
+			ballots: []ballot[string]{
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 1}},
+				{ballot: schulze.Ballot[string]{"B": 1, "C": 1, "A": 2}},
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 2, "C": 2}},
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 200, "C": 10}},
 			},
 			result: []schulze.Result[string]{
 				{Choice: "A", Index: 0, Wins: 4},
@@ -115,11 +119,11 @@ func TestVoting(t *testing.T) {
 		{
 			name:    "duplicate choice", // only the first of the duplicate choices should receive votes
 			choices: []string{"A", "B", "C", "C", "C"},
-			ballots: []schulze.Ballot[string]{
-				{"A": 1, "B": 1},
-				{"B": 1, "C": 1, "A": 2},
-				{"A": 1, "B": 2, "C": 2},
-				{"A": 1, "B": 200, "C": 10},
+			ballots: []ballot[string]{
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 1}},
+				{ballot: schulze.Ballot[string]{"B": 1, "C": 1, "A": 2}},
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 2, "C": 2}},
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 200, "C": 10}},
 			},
 			result: []schulze.Result[string]{
 				{Choice: "A", Index: 0, Wins: 4},
@@ -132,59 +136,59 @@ func TestVoting(t *testing.T) {
 		{
 			name:    "example from wiki page",
 			choices: []string{"A", "B", "C", "D", "E"},
-			ballots: []schulze.Ballot[string]{
-				{"A": 1, "C": 2, "B": 3, "E": 4, "D": 5},
-				{"A": 1, "C": 2, "B": 3, "E": 4, "D": 5},
-				{"A": 1, "C": 2, "B": 3, "E": 4, "D": 5},
-				{"A": 1, "C": 2, "B": 3, "E": 4, "D": 5},
-				{"A": 1, "C": 2, "B": 3, "E": 4, "D": 5},
-
-				{"A": 1, "D": 2, "E": 3, "C": 4, "B": 5},
-				{"A": 1, "D": 2, "E": 3, "C": 4, "B": 5},
-				{"A": 1, "D": 2, "E": 3, "C": 4, "B": 5},
-				{"A": 1, "D": 2, "E": 3, "C": 4, "B": 5},
-				{"A": 1, "D": 2, "E": 3, "C": 4, "B": 5},
-
-				{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5},
-				{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5},
-				{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5},
-				{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5},
-				{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5},
-				{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5},
-				{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5},
-				{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5},
-
-				{"C": 1, "A": 2, "B": 3, "E": 4, "D": 5},
-				{"C": 1, "A": 2, "B": 3, "E": 4, "D": 5},
-				{"C": 1, "A": 2, "B": 3, "E": 4, "D": 5},
-
-				{"C": 1, "A": 2, "E": 3, "B": 4, "D": 5},
-				{"C": 1, "A": 2, "E": 3, "B": 4, "D": 5},
-				{"C": 1, "A": 2, "E": 3, "B": 4, "D": 5},
-				{"C": 1, "A": 2, "E": 3, "B": 4, "D": 5},
-				{"C": 1, "A": 2, "E": 3, "B": 4, "D": 5},
-				{"C": 1, "A": 2, "E": 3, "B": 4, "D": 5},
-				{"C": 1, "A": 2, "E": 3, "B": 4, "D": 5},
-
-				{"C": 1, "B": 2, "A": 3, "D": 4, "E": 5},
-				{"C": 1, "B": 2, "A": 3, "D": 4, "E": 5},
-
-				{"D": 1, "C": 2, "E": 3, "B": 4, "A": 5},
-				{"D": 1, "C": 2, "E": 3, "B": 4, "A": 5},
-				{"D": 1, "C": 2, "E": 3, "B": 4, "A": 5},
-				{"D": 1, "C": 2, "E": 3, "B": 4, "A": 5},
-				{"D": 1, "C": 2, "E": 3, "B": 4, "A": 5},
-				{"D": 1, "C": 2, "E": 3, "B": 4, "A": 5},
-				{"D": 1, "C": 2, "E": 3, "B": 4, "A": 5},
-
-				{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5},
-				{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5},
-				{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5},
-				{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5},
-				{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5},
-				{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5},
-				{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5},
-				{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5},
+			ballots: []ballot[string]{
+				{ballot: schulze.Ballot[string]{"A": 1, "C": 2, "B": 3, "E": 4, "D": 5}},
+				{ballot: schulze.Ballot[string]{"A": 1, "C": 2, "B": 3, "E": 4, "D": 5}},
+				{ballot: schulze.Ballot[string]{"A": 1, "C": 2, "B": 3, "E": 4, "D": 5}},
+				{ballot: schulze.Ballot[string]{"A": 1, "C": 2, "B": 3, "E": 4, "D": 5}},
+				{ballot: schulze.Ballot[string]{"A": 1, "C": 2, "B": 3, "E": 4, "D": 5}},
+
+				{ballot: schulze.Ballot[string]{"A": 1, "D": 2, "E": 3, "C": 4, "B": 5}},
+				{ballot: schulze.Ballot[string]{"A": 1, "D": 2, "E": 3, "C": 4, "B": 5}},
+				{ballot: schulze.Ballot[string]{"A": 1, "D": 2, "E": 3, "C": 4, "B": 5}},
+				{ballot: schulze.Ballot[string]{"A": 1, "D": 2, "E": 3, "C": 4, "B": 5}},
+				{ballot: schulze.Ballot[string]{"A": 1, "D": 2, "E": 3, "C": 4, "B": 5}},
+
+				{ballot: schulze.Ballot[string]{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5}},
+				{ballot: schulze.Ballot[string]{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5}},
+				{ballot: schulze.Ballot[string]{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5}},
+				{ballot: schulze.Ballot[string]{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5}},
+				{ballot: schulze.Ballot[string]{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5}},
+				{ballot: schulze.Ballot[string]{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5}},
+				{ballot: schulze.Ballot[string]{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5}},
+				{ballot: schulze.Ballot[string]{"B": 1, "E": 2, "D": 3, "A": 4, "C": 5}},
+
+				{ballot: schulze.Ballot[string]{"C": 1, "A": 2, "B": 3, "E": 4, "D": 5}},
+				{ballot: schulze.Ballot[string]{"C": 1, "A": 2, "B": 3, "E": 4, "D": 5}},
+				{ballot: schulze.Ballot[string]{"C": 1, "A": 2, "B": 3, "E": 4, "D": 5}},
+
+				{ballot: schulze.Ballot[string]{"C": 1, "A": 2, "E": 3, "B": 4, "D": 5}},
+				{ballot: schulze.Ballot[string]{"C": 1, "A": 2, "E": 3, "B": 4, "D": 5}},
+				{ballot: schulze.Ballot[string]{"C": 1, "A": 2, "E": 3, "B": 4, "D": 5}},
+				{ballot: schulze.Ballot[string]{"C": 1, "A": 2, "E": 3, "B": 4, "D": 5}},
+				{ballot: schulze.Ballot[string]{"C": 1, "A": 2, "E": 3, "B": 4, "D": 5}},
+				{ballot: schulze.Ballot[string]{"C": 1, "A": 2, "E": 3, "B": 4, "D": 5}},
+				{ballot: schulze.Ballot[string]{"C": 1, "A": 2, "E": 3, "B": 4, "D": 5}},
+
+				{ballot: schulze.Ballot[string]{"C": 1, "B": 2, "A": 3, "D": 4, "E": 5}},
+				{ballot: schulze.Ballot[string]{"C": 1, "B": 2, "A": 3, "D": 4, "E": 5}},
+
+				{ballot: schulze.Ballot[string]{"D": 1, "C": 2, "E": 3, "B": 4, "A": 5}},
+				{ballot: schulze.Ballot[string]{"D": 1, "C": 2, "E": 3, "B": 4, "A": 5}},
+				{ballot: schulze.Ballot[string]{"D": 1, "C": 2, "E": 3, "B": 4, "A": 5}},
+				{ballot: schulze.Ballot[string]{"D": 1, "C": 2, "E": 3, "B": 4, "A": 5}},
+				{ballot: schulze.Ballot[string]{"D": 1, "C": 2, "E": 3, "B": 4, "A": 5}},
+				{ballot: schulze.Ballot[string]{"D": 1, "C": 2, "E": 3, "B": 4, "A": 5}},
+				{ballot: schulze.Ballot[string]{"D": 1, "C": 2, "E": 3, "B": 4, "A": 5}},
+
+				{ballot: schulze.Ballot[string]{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5}},
+				{ballot: schulze.Ballot[string]{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5}},
+				{ballot: schulze.Ballot[string]{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5}},
+				{ballot: schulze.Ballot[string]{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5}},
+				{ballot: schulze.Ballot[string]{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5}},
+				{ballot: schulze.Ballot[string]{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5}},
+				{ballot: schulze.Ballot[string]{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5}},
+				{ballot: schulze.Ballot[string]{"E": 1, "B": 2, "A": 3, "D": 4, "C": 5}},
 			},
 			result: []schulze.Result[string]{
 				{Choice: "E", Index: 4, Wins: 4},
@@ -194,14 +198,82 @@ func TestVoting(t *testing.T) {
 				{Choice: "D", Index: 3, Wins: 0},
 			},
 		},
+		{
+			name:    "unvote single option one vote",
+			choices: []string{"A"},
+			ballots: []ballot[string]{
+				{ballot: schulze.Ballot[string]{"A": 1}},
+				{ballot: schulze.Ballot[string]{"A": 1}, unvote: true},
+			},
+			result: []schulze.Result[string]{
+				{Choice: "A", Index: 0, Wins: 0},
+			},
+		},
+		{
+			name:    "unvote two options one vote",
+			choices: []string{"A", "B"},
+			ballots: []ballot[string]{
+				{ballot: schulze.Ballot[string]{"A": 1}},
+				{ballot: schulze.Ballot[string]{"A": 1}, unvote: true},
+			},
+			result: []schulze.Result[string]{
+				{Choice: "A", Index: 0, Wins: 0},
+				{Choice: "B", Index: 1, Wins: 0},
+			},
+			tie: true,
+		},
+		{
+			name:    "unvote complex",
+			choices: []string{"A", "B", "C", "D", "E"},
+			ballots: []ballot[string]{
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 1}},
+				{ballot: schulze.Ballot[string]{"B": 1, "C": 1, "A": 2}},
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 2, "C": 2}},
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 200, "C": 10}},
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 2, "C": 2}, unvote: true},
+			},
+			result: []schulze.Result[string]{
+				{Choice: "A", Index: 0, Wins: 3},
+				{Choice: "B", Index: 1, Wins: 2},
+				{Choice: "C", Index: 2, Wins: 2},
+				{Choice: "D", Index: 3, Wins: 0},
+				{Choice: "E", Index: 4, Wins: 0},
+			},
+		},
+		{
+			name:    "multiple unvote complex",
+			choices: []string{"A", "B", "C", "D", "E"},
+			ballots: []ballot[string]{
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 1}},
+				{ballot: schulze.Ballot[string]{"B": 1, "C": 1, "A": 2}},
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 2, "C": 2}},
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 1}, unvote: true},
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 200, "C": 10}},
+				{ballot: schulze.Ballot[string]{"A": 1, "B": 2, "C": 2}, unvote: true},
+				{ballot: schulze.Ballot[string]{"B": 1, "C": 1, "A": 2}, unvote: true},
+			},
+			result: []schulze.Result[string]{
+				{Choice: "A", Index: 0, Wins: 4},
+				{Choice: "C", Index: 2, Wins: 3},
+				{Choice: "B", Index: 1, Wins: 2},
+				{Choice: "D", Index: 3, Wins: 0},
+				{Choice: "E", Index: 4, Wins: 0},
+			},
+		},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
 			t.Run("functional", func(t *testing.T) {
 				preferences := schulze.NewPreferences(len(tc.choices))
 
 				for _, b := range tc.ballots {
-					if err := schulze.Vote(preferences, tc.choices, b); err != nil {
-						t.Fatal(err)
+					if b.unvote {
+						if err := schulze.Unvote(preferences, tc.choices, b.ballot); err != nil {
+							t.Fatal(err)
+						}
+					} else {
+						if err := schulze.Vote(preferences, tc.choices, b.ballot); err != nil {
+							t.Fatal(err)
+						}
 					}
 				}
 
@@ -217,8 +289,14 @@ func TestVoting(t *testing.T) {
 				v := schulze.NewVoting(tc.choices)
 
 				for _, b := range tc.ballots {
-					if err := v.Vote(b); err != nil {
-						t.Fatal(err)
+					if b.unvote {
+						if err := v.Unvote(b.ballot); err != nil {
+							t.Fatal(err)
+						}
+					} else {
+						if err := v.Vote(b.ballot); err != nil {
+							t.Fatal(err)
+						}
 					}
 				}
 
diff --git a/voting.go b/voting.go
index cd7e23e..234a538 100644
--- a/voting.go
+++ b/voting.go
@@ -27,6 +27,11 @@ func (v *Voting[C]) Vote(b Ballot[C]) error {
 	return Vote(v.preferences, v.choices, b)
 }
 
+// Unvote removes a voting preferences from a single voting ballot.
+func (v *Voting[C]) Unvote(b Ballot[C]) error {
+	return Unvote(v.preferences, v.choices, b)
+}
+
 // Compute calculates a sorted list of choices with the total number of wins for
 // each of them. If there are multiple winners, tie boolean parameter is true.
 func (v *Voting[C]) Compute() (results []Result[C], tie bool) {