diff --git a/swego.go b/swego.go
index ca17be5..40e28a1 100644
--- a/swego.go
+++ b/swego.go
@@ -37,6 +37,13 @@ type CalcFlags struct {
 	FileNameJPL string
 }
 
+// Copy returns a copy of the calculation flags fl.
+func (fl *CalcFlags) Copy() *CalcFlags {
+	copy := new(CalcFlags)
+	*copy = *fl
+	return copy
+}
+
 // Ephemeris represents an ephemeris implemented in the C library.
 type Ephemeris int32
 
diff --git a/swego_test.go b/swego_test.go
index b1c1313..5c9a521 100644
--- a/swego_test.go
+++ b/swego_test.go
@@ -53,8 +53,18 @@ func TestNewHSys(t *testing.T) {
 	}
 }
 
+func TestCalcFlags_Copy(t *testing.T) {
+	fl := new(CalcFlags)
+	fl.Flags = FlagSpeed
+	got := fl.Copy()
+
+	if got == fl {
+		t.Errorf("%p = %p, want copy", got, fl)
+	}
+}
+
 func TestCalcFlags_SetEphemeris(t *testing.T) {
-	fl := CalcFlags{}
+	fl := new(CalcFlags)
 	fl.SetEphemeris(JPL)
 
 	if fl.Flags != int32(JPL) {