diff --git a/libsigrok.h b/libsigrok.h
index 2ab75a89..3d577ccc 100644
--- a/libsigrok.h
+++ b/libsigrok.h
@@ -594,7 +594,7 @@ enum {
 
 	/*--- Device configuration ------------------------------------------*/
 
-	/** The device supports setting/changing its samplerate. */
+	/** The device supports setting its samplerate, in Hz. */
 	SR_CONF_SAMPLERATE = 30000,
 
 	/** The device supports setting a pre/post-trigger capture ratio. */
@@ -633,6 +633,9 @@ enum {
 	/** Trigger types.  */
 	SR_CONF_TRIGGER_TYPE,
 
+	/** The device supports setting its sample interval, in ms. */
+	SR_CONF_SAMPLE_INTERVAL,
+
 	/*--- Special stuff -------------------------------------------------*/
 
 	/** Scan options supported by the driver. */