diff --git a/source/SSI263Phonemes.h b/source/SSI263Phonemes.h
index 2ae5cfcd..e1bccfb1 100644
--- a/source/SSI263Phonemes.h
+++ b/source/SSI263Phonemes.h
@@ -1,3 +1,5 @@
+#pragma once
+
 typedef struct
 {
 	unsigned int nOffset;