diff --git a/types.go b/types.go
index ee604c1671..399d247d2c 100644
--- a/types.go
+++ b/types.go
@@ -1418,6 +1418,12 @@ func (t *FunctionType) Equal(other Type) bool {
 		}
 	}
 
+	// Purity
+
+	if t.Purity != otherType.Purity {
+		return false
+	}
+
 	return t.ReturnType.Equal(otherType.ReturnType)
 }
 
diff --git a/types_test.go b/types_test.go
index d8ab110629..98e2e927f3 100644
--- a/types_test.go
+++ b/types_test.go
@@ -149,6 +149,16 @@ func TestType_ID(t *testing.T) {
 			},
 			"fun(Int):String",
 		},
+		{
+			&FunctionType{
+				Parameters: []Parameter{
+					{Type: IntType},
+				},
+				ReturnType: StringType,
+				Purity:     FunctionPurityView,
+			},
+			"view fun(Int):String",
+		},
 		{
 			&EventType{
 				QualifiedIdentifier: "Event",
@@ -1526,6 +1536,36 @@ func TestTypeEquality(t *testing.T) {
 			target := AnyType
 			assert.False(t, source.Equal(target))
 		})
+
+		t.Run("different purity", func(t *testing.T) {
+			t.Parallel()
+
+			source := &FunctionType{
+				Purity:     FunctionPurityView,
+				ReturnType: StringType,
+				Parameters: []Parameter{
+					{
+						Type: IntType,
+					},
+					{
+						Type: BoolType,
+					},
+				},
+			}
+			target := &FunctionType{
+				Purity:     FunctionPurityUnspecified, // default
+				ReturnType: StringType,
+				Parameters: []Parameter{
+					{
+						Type: IntType,
+					},
+					{
+						Type: BoolType,
+					},
+				},
+			}
+			assert.False(t, source.Equal(target))
+		})
 	})
 
 	t.Run("reference type", func(t *testing.T) {