diff --git a/sdk/head/units.h b/sdk/head/units.h
index e4dd8c3..b726163 100644
--- a/sdk/head/units.h
+++ b/sdk/head/units.h
@@ -19,4 +19,7 @@
 #define NSEC_PER_SECOND 1000000000ULL
 #define USEC_PER_SECOND 1000000ULL
 
+/* Frequency units */
+#define HZ_PER_MHZ 1000000
+
 #endif  /* !_SDK_UNITS_H_ */