diff --git a/include/libsigrok/proto.h b/include/libsigrok/proto.h
index 7770e175..8179c815 100644
--- a/include/libsigrok/proto.h
+++ b/include/libsigrok/proto.h
@@ -33,6 +33,7 @@ SR_API int sr_analog_to_float(const struct sr_datafeed_analog2 *analog,
 SR_API int sr_analog_float_to_string(float value, int digits, char **result);
 SR_API int sr_analog_unit_to_string(const struct sr_datafeed_analog2 *analog,
 		char **result);
+SR_API inline void sr_rational_set(struct sr_rational *r, uint64_t p, uint64_t q);
 
 /*--- backend.c -------------------------------------------------------------*/
 
diff --git a/src/analog.c b/src/analog.c
index 9e01566f..01704fd7 100644
--- a/src/analog.c
+++ b/src/analog.c
@@ -229,3 +229,15 @@ SR_API int sr_analog_unit_to_string(const struct sr_datafeed_analog2 *analog,
 	return SR_OK;
 }
 
+/*
+ * Set sr_rational r to the given value.
+ *
+ * @param p Numerator
+ * @param q Denominator
+ */
+SR_API inline void sr_rational_set(struct sr_rational *r, uint64_t p, uint64_t q)
+{
+	r->p = p;
+	r->q = q;
+}
+