Fix header guards for moved headers.
diff --git a/runtime/cpp/emboss_arithmetic.h b/runtime/cpp/emboss_arithmetic.h
index c84df17..dd570ba 100644
--- a/runtime/cpp/emboss_arithmetic.h
+++ b/runtime/cpp/emboss_arithmetic.h
@@ -14,8 +14,8 @@
// Implementations for the operations and builtin functions in the Emboss
// expression language.
-#ifndef EMBOSS_PUBLIC_EMBOSS_ARITHMETIC_H_
-#define EMBOSS_PUBLIC_EMBOSS_ARITHMETIC_H_
+#ifndef EMBOSS_RUNTIME_CPP_EMBOSS_ARITHMETIC_H_
+#define EMBOSS_RUNTIME_CPP_EMBOSS_ARITHMETIC_H_
#include <cstdint>
#include <type_traits>
@@ -322,4 +322,4 @@
} // namespace support
} // namespace emboss
-#endif // EMBOSS_PUBLIC_EMBOSS_ARITHMETIC_H_
+#endif // EMBOSS_RUNTIME_CPP_EMBOSS_ARITHMETIC_H_