diff --git a/geos/wkt.go b/geos/wkt.go
index cf4a2a6..6bf85b5 100644
--- a/geos/wkt.go
+++ b/geos/wkt.go
@@ -31,6 +31,7 @@ func (d *wktDecoder) decode(wkt string) (*Geometry, error) {
 	cstr := C.CString(wkt)
 	defer C.free(unsafe.Pointer(cstr))
 	g := cGEOSWKTReader_read(d.r, cstr)
+	runtime.KeepAlive(d)
 	if g == nil {
 		return nil, Error()
 	}
@@ -60,9 +61,11 @@ func newWktEncoder() *wktEncoder {
 // Encode returns a string that is the geometry encoded as WKT
 func (e *wktEncoder) encode(g *Geometry) (string, error) {
 	cstr := cGEOSWKTWriter_write(e.w, g.g)
+	runtime.KeepAlive(e)
 	if cstr == nil {
 		return "", Error()
 	}
+	defer C.free(unsafe.Pointer(cstr))
 	return C.GoString(cstr), nil
 }