diff --git a/src/personal_message.h b/src/personal_message.h
index d6be0dc..9d31527 100644
--- a/src/personal_message.h
+++ b/src/personal_message.h
@@ -21,6 +21,8 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  *****************************************************************************/
+#pragma once
+
 #include <stdint.h>
 #include <stdbool.h>
 
diff --git a/src/sighash.h b/src/sighash.h
index 7338b41..5743399 100644
--- a/src/sighash.h
+++ b/src/sighash.h
@@ -21,6 +21,8 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  *****************************************************************************/
+#pragma once
+
 #include <stdint.h>
 #include "./transaction/types.h"