diff --git a/src/shunting-yard.c b/src/shunting-yard.c
index c30f821..85534f4 100644
--- a/src/shunting-yard.c
+++ b/src/shunting-yard.c
@@ -53,6 +53,7 @@ static const Token NO_TOKEN = {TOKEN_NONE, NULL};
 static const Operator OPERATORS[] = {
 	{"!", 1, 1, OPERATOR_UNARY,  OPERATOR_RIGHT},
 	{"~", 1, 1, OPERATOR_UNARY,  OPERATOR_RIGHT},
+	{"-", 1, 1, OPERATOR_UNARY,  OPERATOR_RIGHT},
 	{"*", 1, 2, OPERATOR_BINARY, OPERATOR_LEFT},
 	{"/", 1, 2, OPERATOR_BINARY, OPERATOR_LEFT},
 	{"%", 1, 2, OPERATOR_BINARY, OPERATOR_LEFT},
diff --git a/tests/test-shunting-yard.c b/tests/test-shunting-yard.c
index 4345b8d..f9c636a 100644
--- a/tests/test-shunting-yard.c
+++ b/tests/test-shunting-yard.c
@@ -71,6 +71,15 @@ static void test_modulus()
 	ASSERT_RESULT("5 %5", 0);
 }
 
+static void test_negation()
+{
+	ASSERT_RESULT("-1", -1);
+	ASSERT_RESULT("(-1)", -1);
+	ASSERT_RESULT("(-1) + 1", 0);
+	ASSERT_RESULT("(-1) + (-1)", -2);
+	ASSERT_RESULT("-1 + -1", -2);
+	ASSERT_RESULT("-1 + --1", 0);
+}
 
 static void test_functions()
 {