diff --git a/src/hw_ostc_parser.c b/src/hw_ostc_parser.c
index 0210937..aff1b8c 100644
--- a/src/hw_ostc_parser.c
+++ b/src/hw_ostc_parser.c
@@ -112,6 +112,7 @@ typedef struct hw_ostc_gasmix_t {
 	unsigned int helium;
 	unsigned int type;
 	unsigned int enabled;
+	unsigned int diluent;
 } hw_ostc_gasmix_t;
 
 typedef struct hw_ostc_parser_t {
@@ -195,7 +196,7 @@ static const hw_ostc_layout_t hw_ostc_layout_ostc3 = {
 };
 
 static unsigned int
-hw_ostc_find_gasmix (hw_ostc_parser_t *parser, unsigned int o2, unsigned int he, unsigned int type)
+hw_ostc_find_gasmix (hw_ostc_parser_t *parser, unsigned int o2, unsigned int he, unsigned int dil, unsigned int type)
 {
 	unsigned int offset = 0;
 	unsigned int count = parser->ngasmixes;
@@ -207,7 +208,7 @@ hw_ostc_find_gasmix (hw_ostc_parser_t *parser, unsigned int o2, unsigned int he,
 
 	unsigned int i = offset;
 	while (i < count) {
-		if (o2 == parser->gasmix[i].oxygen && he == parser->gasmix[i].helium)
+		if (o2 == parser->gasmix[i].oxygen && he == parser->gasmix[i].helium && dil == parser->gasmix[i].diluent)
 			break;
 		i++;
 	}
@@ -215,6 +216,18 @@ hw_ostc_find_gasmix (hw_ostc_parser_t *parser, unsigned int o2, unsigned int he,
 	return i;
 }
 
+static unsigned int
+hw_ostc_is_ccr (unsigned int divemode, unsigned int version)
+{
+	if (version == 0x21) {
+		return divemode == OSTC_ZHL16_CC || divemode == OSTC_ZHL16_CC_GF || divemode == OSTC_PSCR_GF;
+	} else if (version == 0x23 || version == 0x24) {
+		return divemode == OSTC3_CC || divemode == OSTC3_PSCR;
+	} else {
+		return 0;
+	}
+}
+
 static dc_status_t
 hw_ostc_parser_cache (hw_ostc_parser_t *parser)
 {
@@ -263,6 +276,13 @@ hw_ostc_parser_cache (hw_ostc_parser_t *parser)
 		return DC_STATUS_DATAFORMAT;
 	}
 
+	// Get the dive mode.
+	unsigned int divemode = layout->divemode < header ?
+		data[layout->divemode] : UNDEFINED;
+
+	// Get the CCR mode.
+	unsigned int ccr = hw_ostc_is_ccr (divemode, version);
+
 	// Get all the gas mixes, the index of the inital mix,
 	// the initial setpoint (used in the fixed setpoint CCR mode),
 	// and the initial CNS from the header
@@ -281,6 +301,7 @@ hw_ostc_parser_cache (hw_ostc_parser_t *parser)
 			gasmix[i].helium = 0;
 			gasmix[i].type = 0;
 			gasmix[i].enabled = 1;
+			gasmix[i].diluent = 0;
 		}
 	} else if (version == 0x23 || version == 0x24) {
 		ngasmixes = 5;
@@ -289,13 +310,14 @@ hw_ostc_parser_cache (hw_ostc_parser_t *parser)
 			gasmix[i].helium = data[28 + 4 * i + 1];
 			gasmix[i].type   = data[28 + 4 * i + 3];
 			gasmix[i].enabled = gasmix[i].type != 0;
+			gasmix[i].diluent = ccr;
 			// Find the first gas marked as the initial gas.
 			if (initial == UNDEFINED && data[28 + 4 * i + 3] == 1) {
 				initial = i + 1; /* One based index! */
 			}
 		}
 		// The first fixed setpoint is the initial setpoint in CCR mode.
-		if (data[layout->divemode] == OSTC3_CC || data[layout->divemode] == OSTC3_PSCR) {
+		if (ccr) {
 			initial_setpoint = data[60];
 		}
 		// Initial CNS
@@ -314,6 +336,7 @@ hw_ostc_parser_cache (hw_ostc_parser_t *parser)
 			} else {
 				gasmix[i].enabled = 1;
 			}
+			gasmix[i].diluent = ccr;
 		}
 	}
 	if (initial != UNDEFINED) {
@@ -375,6 +398,7 @@ hw_ostc_parser_create_internal (dc_parser_t **out, dc_context_t *context, unsign
 		parser->gasmix[i].helium = 0;
 		parser->gasmix[i].type = 0;
 		parser->gasmix[i].enabled = 0;
+		parser->gasmix[i].diluent = 0;
 	}
 
 	*out = (dc_parser_t *) parser;
@@ -415,6 +439,7 @@ hw_ostc_parser_set_data (dc_parser_t *abstract, const unsigned char *data, unsig
 		parser->gasmix[i].helium = 0;
 		parser->gasmix[i].type = 0;
 		parser->gasmix[i].enabled = 0;
+		parser->gasmix[i].diluent = 0;
 	}
 
 	return DC_STATUS_SUCCESS;
@@ -787,6 +812,13 @@ hw_ostc_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_t call
 		firmware = array_uint16_be (data + layout->firmware);
 	}
 
+	// Get the dive mode.
+	unsigned int divemode = layout->divemode < header ?
+		data[layout->divemode] : UNDEFINED;
+
+	// Get the CCR mode.
+	unsigned int ccr = hw_ostc_is_ccr (divemode, version);
+
 	unsigned int time = 0;
 	unsigned int nsamples = 0;
 	unsigned int tank = parser->initial != UNDEFINED ? parser->initial : 0;
@@ -894,7 +926,7 @@ hw_ostc_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_t call
 			}
 			unsigned int o2 = data[offset];
 			unsigned int he = data[offset + 1];
-			unsigned int idx = hw_ostc_find_gasmix (parser, o2, he, MANUAL);
+			unsigned int idx = hw_ostc_find_gasmix (parser, o2, he, ccr, MANUAL);
 			if (idx >= parser->ngasmixes) {
 				if (idx >= NGASMIXES) {
 					ERROR (abstract->context, "Maximum number of gas mixes reached.");
@@ -904,6 +936,7 @@ hw_ostc_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_t call
 				parser->gasmix[idx].helium = he;
 				parser->gasmix[idx].type = 0;
 				parser->gasmix[idx].enabled = 1;
+				parser->gasmix[idx].diluent = ccr;
 				parser->ngasmixes = idx + 1;
 			}
 
@@ -954,7 +987,7 @@ hw_ostc_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_t call
 
 				unsigned int o2 = data[offset];
 				unsigned int he = data[offset + 1];
-				unsigned int idx = hw_ostc_find_gasmix (parser, o2, he, MANUAL);
+				unsigned int idx = hw_ostc_find_gasmix (parser, o2, he, 0, MANUAL);
 				if (idx >= parser->ngasmixes) {
 					if (idx >= NGASMIXES) {
 						ERROR (abstract->context, "Maximum number of gas mixes reached.");
@@ -964,6 +997,7 @@ hw_ostc_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_t call
 					parser->gasmix[idx].helium = he;
 					parser->gasmix[idx].type = 0;
 					parser->gasmix[idx].enabled = 1;
+					parser->gasmix[idx].diluent = 0;
 					parser->ngasmixes = idx + 1;
 				}
 
@@ -1086,7 +1120,7 @@ hw_ostc_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_t call
 
 				unsigned int o2 = data[offset];
 				unsigned int he = data[offset + 1];
-				unsigned int idx = hw_ostc_find_gasmix (parser, o2, he, MANUAL);
+				unsigned int idx = hw_ostc_find_gasmix (parser, o2, he, 0, MANUAL);
 				if (idx >= parser->ngasmixes) {
 					if (idx >= NGASMIXES) {
 						ERROR (abstract->context, "Maximum number of gas mixes reached.");
@@ -1096,6 +1130,7 @@ hw_ostc_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_t call
 					parser->gasmix[idx].helium = he;
 					parser->gasmix[idx].type = 0;
 					parser->gasmix[idx].enabled = 1;
+					parser->gasmix[idx].diluent = 0;
 					parser->ngasmixes = idx + 1;
 				}
 
diff --git a/src/shearwater_predator_parser.c b/src/shearwater_predator_parser.c
index 9432603..06a0882 100644
--- a/src/shearwater_predator_parser.c
+++ b/src/shearwater_predator_parser.c
@@ -106,6 +106,7 @@ typedef struct shearwater_predator_parser_t shearwater_predator_parser_t;
 typedef struct shearwater_predator_gasmix_t {
 	unsigned int oxygen;
 	unsigned int helium;
+	unsigned int diluent;
 } shearwater_predator_gasmix_t;
 
 typedef struct shearwater_predator_tank_t {
@@ -182,11 +183,11 @@ static const dc_parser_vtable_t shearwater_petrel_parser_vtable = {
 
 
 static unsigned int
-shearwater_predator_find_gasmix (shearwater_predator_parser_t *parser, unsigned int o2, unsigned int he)
+shearwater_predator_find_gasmix (shearwater_predator_parser_t *parser, unsigned int o2, unsigned int he, unsigned int dil)
 {
 	unsigned int i = 0;
 	while (i < parser->ngasmixes) {
-		if (o2 == parser->gasmix[i].oxygen && he == parser->gasmix[i].helium)
+		if (o2 == parser->gasmix[i].oxygen && he == parser->gasmix[i].helium && dil == parser->gasmix[i].diluent)
 			break;
 		i++;
 	}
@@ -238,6 +239,7 @@ shearwater_common_parser_create (dc_parser_t **out, dc_context_t *context, unsig
 	for (unsigned int i = 0; i < NGASMIXES; ++i) {
 		parser->gasmix[i].oxygen = 0;
 		parser->gasmix[i].helium = 0;
+		parser->gasmix[i].diluent = 0;
 	}
 	parser->ntanks = 0;
 	for (unsigned int i = 0; i < NTANKS; ++i) {
@@ -301,6 +303,7 @@ shearwater_predator_parser_set_data (dc_parser_t *abstract, const unsigned char
 	for (unsigned int i = 0; i < NGASMIXES; ++i) {
 		parser->gasmix[i].oxygen = 0;
 		parser->gasmix[i].helium = 0;
+		parser->gasmix[i].diluent = 0;
 	}
 	parser->ntanks = 0;
 	for (unsigned int i = 0; i < NTANKS; ++i) {
@@ -425,12 +428,13 @@ shearwater_predator_parser_cache (shearwater_predator_parser_t *parser)
 	unsigned int ngasmixes = NFIXED;
 	shearwater_predator_gasmix_t gasmix[NGASMIXES] = {0};
 	shearwater_predator_tank_t tank[NTANKS] = {0};
-	unsigned int o2_previous = UNDEFINED, he_previous = UNDEFINED;
+	unsigned int o2_previous = UNDEFINED, he_previous = UNDEFINED, dil_previous = UNDEFINED;
 	unsigned int aimode = AI_OFF;
 	if (!pnf) {
 		for (unsigned int i = 0; i < NFIXED; ++i) {
 			gasmix[i].oxygen = data[20 + i];
 			gasmix[i].helium = data[30 + i];
+			gasmix[i].diluent = i >= 5;
 		}
 	}
 
@@ -449,19 +453,20 @@ shearwater_predator_parser_cache (shearwater_predator_parser_t *parser)
 		if (type == LOG_RECORD_DIVE_SAMPLE) {
 			// Status flags.
 			unsigned int status = data[offset + 11 + pnf];
-			if ((status & OC) == 0) {
+			unsigned int ccr = (status & OC) == 0;
+			if (ccr) {
 				divemode = status & SC ? M_SC : M_CC;
 			}
 
 			// Gaschange.
 			unsigned int o2 = data[offset + 7 + pnf];
 			unsigned int he = data[offset + 8 + pnf];
-			if ((o2 != o2_previous || he != he_previous) &&
+			if ((o2 != o2_previous || he != he_previous || ccr != dil_previous) &&
 				(o2 != 0 || he != 0)) {
 				// Find the gasmix in the list.
 				unsigned int idx = 0;
 				while (idx < ngasmixes) {
-					if (o2 == gasmix[idx].oxygen && he == gasmix[idx].helium)
+					if (o2 == gasmix[idx].oxygen && he == gasmix[idx].helium && ccr == gasmix[idx].diluent)
 						break;
 					idx++;
 				}
@@ -474,11 +479,13 @@ shearwater_predator_parser_cache (shearwater_predator_parser_t *parser)
 					}
 					gasmix[idx].oxygen = o2;
 					gasmix[idx].helium = he;
+					gasmix[idx].diluent = ccr;
 					ngasmixes = idx + 1;
 				}
 
 				o2_previous = o2;
 				he_previous = he;
+				dil_previous = ccr;
 			}
 
 			// Tank pressure
@@ -551,6 +558,7 @@ shearwater_predator_parser_cache (shearwater_predator_parser_t *parser)
 			if (type == LOG_RECORD_OPENING_0) {
 				for (unsigned int i = 0; i < NFIXED; ++i) {
 					gasmix[i].oxygen = data[offset + 20 + i];
+					gasmix[i].diluent = i >= 5;
 				}
 				for (unsigned int i = 0; i < 2; ++i) {
 					gasmix[i].helium = data[offset + 30 + i];
@@ -859,7 +867,7 @@ shearwater_predator_parser_samples_foreach (dc_parser_t *abstract, dc_sample_cal
 		return rc;
 
 	// Previous gas mix.
-	unsigned int o2_previous = UNDEFINED, he_previous = UNDEFINED;
+	unsigned int o2_previous = UNDEFINED, he_previous = UNDEFINED, dil_previous = UNDEFINED;
 
 	// Sample interval.
 	unsigned int time = 0;
@@ -919,8 +927,9 @@ shearwater_predator_parser_samples_foreach (dc_parser_t *abstract, dc_sample_cal
 
 			// Status flags.
 			unsigned int status = data[offset + pnf + 11];
+			unsigned int ccr = (status & OC) == 0;
 
-			if ((status & OC) == 0) {
+			if (ccr) {
 				// PPO2
 				if ((status & PPO2_EXTERNAL) == 0) {
 #ifdef SENSOR_AVERAGE
@@ -961,9 +970,9 @@ shearwater_predator_parser_samples_foreach (dc_parser_t *abstract, dc_sample_cal
 			// Gaschange.
 			unsigned int o2 = data[offset + pnf + 7];
 			unsigned int he = data[offset + pnf + 8];
-			if ((o2 != o2_previous || he != he_previous) &&
+			if ((o2 != o2_previous || he != he_previous || ccr != dil_previous) &&
 				(o2 != 0 || he != 0)) {
-				unsigned int idx = shearwater_predator_find_gasmix (parser, o2, he);
+				unsigned int idx = shearwater_predator_find_gasmix (parser, o2, he, ccr);
 				if (idx >= parser->ngasmixes) {
 					ERROR (abstract->context, "Invalid gas mix.");
 					return DC_STATUS_DATAFORMAT;
@@ -973,6 +982,7 @@ shearwater_predator_parser_samples_foreach (dc_parser_t *abstract, dc_sample_cal
 				if (callback) callback (DC_SAMPLE_GASMIX, sample, userdata);
 				o2_previous = o2;
 				he_previous = he;
+				dil_previous = ccr;
 			}
 
 			// Deco stop / NDL.