diff --git a/examples/output_xml.c b/examples/output_xml.c
index 882680a..f4c312d 100644
--- a/examples/output_xml.c
+++ b/examples/output_xml.c
@@ -157,7 +157,11 @@ sample_cb (dc_sample_type_t type, dc_sample_value_t value, void *userdata)
 		fprintf (sampledata->ostream, "   <setpoint>%.2f</setpoint>\n", value.setpoint);
 		break;
 	case DC_SAMPLE_PPO2:
-		fprintf (sampledata->ostream, "   <ppo2>%.2f</ppo2>\n", value.ppo2);
+		if (value.ppo2.sensor != DC_SENSOR_NONE) {
+			fprintf (sampledata->ostream, "   <ppo2 sensor=\"%u\">%.2f</ppo2>\n", value.ppo2.sensor, value.ppo2.value);
+		} else {
+			fprintf (sampledata->ostream, "   <ppo2>%.2f</ppo2>\n", value.ppo2.value);
+		}
 		break;
 	case DC_SAMPLE_CNS:
 		fprintf (sampledata->ostream, "   <cns>%.1f</cns>\n", value.cns * 100.0);
diff --git a/include/libdivecomputer/parser.h b/include/libdivecomputer/parser.h
index de1bbc1..c4d0a72 100644
--- a/include/libdivecomputer/parser.h
+++ b/include/libdivecomputer/parser.h
@@ -147,6 +147,7 @@ typedef struct dc_gasmix_t {
 	double nitrogen;
 } dc_gasmix_t;
 
+#define DC_SENSOR_NONE    0xFFFFFFFF
 #define DC_GASMIX_UNKNOWN 0xFFFFFFFF
 
 typedef enum dc_tankvolume_t {
@@ -247,7 +248,10 @@ typedef union dc_sample_value_t {
 		const void *data;
 	} vendor;
 	double setpoint;
-	double ppo2;
+	struct {
+		unsigned int sensor;
+		double value;
+	} ppo2;
 	double cns;
 	struct {
 		unsigned int type;
diff --git a/src/diverite_nitekq_parser.c b/src/diverite_nitekq_parser.c
index dec8204..6cfd9bc 100644
--- a/src/diverite_nitekq_parser.c
+++ b/src/diverite_nitekq_parser.c
@@ -293,7 +293,8 @@ diverite_nitekq_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callbac
 				if (offset + 1 > size)
 					return DC_STATUS_DATAFORMAT;
 				unsigned int ppo2 = data[offset];
-				sample.ppo2 = ppo2 / 100.0;
+				sample.ppo2.sensor = DC_SENSOR_NONE;
+				sample.ppo2.value = ppo2 / 100.0;
 				if (callback) callback (DC_SAMPLE_PPO2, sample, userdata);
 				offset++;
 			}
diff --git a/src/divesoft_freedom_parser.c b/src/divesoft_freedom_parser.c
index 6280dbf..1f0b7b3 100644
--- a/src/divesoft_freedom_parser.c
+++ b/src/divesoft_freedom_parser.c
@@ -946,7 +946,8 @@ divesoft_freedom_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callba
 			if (callback) callback(DC_SAMPLE_DEPTH, sample, userdata);
 
 			if (ppo2) {
-				sample.ppo2 = ppo2 * 10.0 / BAR;
+				sample.ppo2.sensor = DC_SENSOR_NONE;
+				sample.ppo2.value = ppo2 * 10.0 / BAR;
 				if (callback) callback(DC_SAMPLE_PPO2, sample, userdata);
 			}
 
@@ -1045,7 +1046,8 @@ divesoft_freedom_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callba
 					unsigned int ppo2 = array_uint16_le (data + offset + 4 + i * 2);
 					if (ppo2 == 0 || ppo2 == 0xFFFF)
 						continue;
-					sample.ppo2 = ppo2 * 10.0 / BAR;
+					sample.ppo2.sensor = i;
+					sample.ppo2.value = ppo2 * 10.0 / BAR;
 					if (callback) callback(DC_SAMPLE_PPO2, sample, userdata);
 				}
 			} else if (id == MEASURE_ID_OXYGEN_MV) {
@@ -1055,7 +1057,8 @@ divesoft_freedom_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callba
 					if (!parser->calibrated || state == SENSTAT_UNCALIBRATED ||
 						state == SENSTAT_NOT_EXIST)
 						continue;
-					sample.ppo2 = value / 100.0 * parser->calibration[i] / BAR;
+					sample.ppo2.sensor = i;
+					sample.ppo2.value = value / 100.0 * parser->calibration[i] / BAR;
 					if (callback) callback(DC_SAMPLE_PPO2, sample, userdata);
 				}
 			}
diff --git a/src/hw_ostc_parser.c b/src/hw_ostc_parser.c
index de354df..0ee02ac 100644
--- a/src/hw_ostc_parser.c
+++ b/src/hw_ostc_parser.c
@@ -1067,7 +1067,8 @@ hw_ostc_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_t call
 					}
 					if (count) {
 						for (unsigned int j = 0; j < 3; ++j) {
-							sample.ppo2 = ppo2[j] / 100.0;
+							sample.ppo2.sensor = i;
+							sample.ppo2.value = ppo2[j] / 100.0;
 							if (callback) callback (DC_SAMPLE_PPO2, sample, userdata);
 						}
 					}
diff --git a/src/shearwater_predator_parser.c b/src/shearwater_predator_parser.c
index 0975ff9..ab7752f 100644
--- a/src/shearwater_predator_parser.c
+++ b/src/shearwater_predator_parser.c
@@ -927,19 +927,21 @@ shearwater_predator_parser_samples_foreach (dc_parser_t *abstract, dc_sample_cal
 			if (ccr) {
 				// PPO2
 				if ((status & PPO2_EXTERNAL) == 0) {
-#ifdef SENSOR_AVERAGE
-					sample.ppo2 = data[offset + pnf + 6] / 100.0;
+					sample.ppo2.sensor = DC_SENSOR_NONE;
+					sample.ppo2.value = data[offset + pnf + 6] / 100.0;
 					if (callback) callback (DC_SAMPLE_PPO2, sample, userdata);
-#else
-					sample.ppo2 = data[offset + pnf + 12] * parser->calibration[0];
+
+					sample.ppo2.sensor = 0;
+					sample.ppo2.value = data[offset + pnf + 12] * parser->calibration[0];
 					if (callback && (parser->calibrated & 0x01)) callback (DC_SAMPLE_PPO2, sample, userdata);
 
-					sample.ppo2 = data[offset + pnf + 14] * parser->calibration[1];
+					sample.ppo2.sensor = 1;
+					sample.ppo2.value = data[offset + pnf + 14] * parser->calibration[1];
 					if (callback && (parser->calibrated & 0x02)) callback (DC_SAMPLE_PPO2, sample, userdata);
 
-					sample.ppo2 = data[offset + pnf + 15] * parser->calibration[2];
+					sample.ppo2.sensor = 2;
+					sample.ppo2.value = data[offset + pnf + 15] * parser->calibration[2];
 					if (callback && (parser->calibrated & 0x04)) callback (DC_SAMPLE_PPO2, sample, userdata);
-#endif
 				}
 
 				// Setpoint
diff --git a/src/tecdiving_divecomputereu_parser.c b/src/tecdiving_divecomputereu_parser.c
index bf134eb..ccfbb05 100644
--- a/src/tecdiving_divecomputereu_parser.c
+++ b/src/tecdiving_divecomputereu_parser.c
@@ -174,7 +174,8 @@ tecdiving_divecomputereu_parser_samples_foreach (dc_parser_t *abstract, dc_sampl
 
 		// ppO2
 		unsigned int ppo2 = data[offset + 1];
-		sample.ppo2 = ppo2 / 10.0;
+		sample.ppo2.sensor = DC_SENSOR_NONE;
+		sample.ppo2.value = ppo2 / 10.0;
 		if (callback) callback (DC_SAMPLE_PPO2, sample, userdata);
 
 		// Setpoint