diff --git a/src/mares_nemo.c b/src/mares_nemo.c
index 165e4e7..d1327cf 100644
--- a/src/mares_nemo.c
+++ b/src/mares_nemo.c
@@ -39,6 +39,10 @@
 #define MEMORYSIZE 0x4000
 #define PACKETSIZE 0x20
 
+#define NEMO        0
+#define NEMOEXCEL   17
+#define NEMOAPNEIST 18
+
 typedef struct mares_nemo_device_t {
 	mares_common_device_t base;
 	serial_t *port;
@@ -309,11 +313,11 @@ mares_nemo_extract_dives (device_t *abstract, const unsigned char data[], unsign
 
 	const mares_common_layout_t *layout = NULL;
 	switch (data[1]) {
-	case 0: // Nemo
-	case 17: // Nemo Excel
+	case NEMO:
+	case NEMOEXCEL:
 		layout = &mares_nemo_layout;
 		break;
-	case 18: // Nemo Apneist
+	case NEMOAPNEIST:
 		layout = &mares_nemo_apneist_layout;
 		break;
 	default: // Unknown, try nemo
diff --git a/src/mares_nemo_parser.c b/src/mares_nemo_parser.c
index 812d70b..4ffcf13 100644
--- a/src/mares_nemo_parser.c
+++ b/src/mares_nemo_parser.c
@@ -28,6 +28,14 @@
 #include "utils.h"
 #include "array.h"
 
+#define NEMO        0
+#define NEMOWIDE    1
+#define NEMOAIR     4
+#define PUCK        7
+#define NEMOEXCEL   17
+#define NEMOAPNEIST 18
+#define PUCKAIR     19
+
 typedef struct mares_nemo_parser_t mares_nemo_parser_t;
 
 struct mares_nemo_parser_t {
@@ -87,7 +95,7 @@ mares_nemo_parser_create (parser_t **out, unsigned int model)
 
 	// Get the freedive mode for this model.
 	unsigned int freedive = 2;
-	if (model == 1 || model == 7)
+	if (model == NEMOWIDE || model == PUCK)
 		freedive = 3;
 
 	// Set the default values.
@@ -147,7 +155,7 @@ mares_nemo_parser_set_data (parser_t *abstract, const unsigned char *data, unsig
 	unsigned int extra = 0;
 	const unsigned char marker[3] = {0xAA, 0xBB, 0xCC};
 	if (memcmp (data + length - 3, marker, sizeof (marker)) == 0) {
-		if (parser->model == 19)
+		if (parser->model == PUCKAIR)
 			extra = 7;
 		else
 			extra = 12;
@@ -161,7 +169,7 @@ mares_nemo_parser_set_data (parser_t *abstract, const unsigned char *data, unsig
 	unsigned int header_size = 53;
 	unsigned int sample_size = 2;
 	if (extra) {
-		if (parser->model == 19)
+		if (parser->model == PUCKAIR)
 			sample_size = 3;
 		else
 			sample_size = 5;
@@ -368,7 +376,7 @@ mares_nemo_parser_samples_foreach (parser_t *abstract, sample_callback_t callbac
 			if (profiles) {
 				// Get the freedive sample interval for this model.
 				unsigned int interval = 4;
-				if (parser->model == 18)
+				if (parser->model == NEMOAPNEIST)
 					interval = 1;
 
 				// Calculate the number of samples that should be present
diff --git a/src/mares_puck.c b/src/mares_puck.c
index 82925e9..766b155 100644
--- a/src/mares_puck.c
+++ b/src/mares_puck.c
@@ -39,6 +39,11 @@
 #define PACKETSIZE 0x20
 #define MAXRETRIES 4
 
+#define NEMOWIDE    1
+#define NEMOAIR     4
+#define PUCK        7
+#define PUCKAIR     19
+
 typedef struct mares_puck_device_t {
 	mares_common_device_t base;
 	serial_t *port;
@@ -161,13 +166,13 @@ mares_puck_device_open (device_t **out, const char* name)
 
 	// Override the base class values.
 	switch (header[1]) {
-	case 1: // Nemo Wide
+	case NEMOWIDE:
 		device->base.layout = &mares_nemowide_layout;
 		break;
-	case 4: // Nemo Air
+	case NEMOAIR:
 		device->base.layout = &mares_nemoair_layout;
 		break;
-	case 7: // Puck
+	case PUCK:
 		device->base.layout = &mares_puck_layout;
 		break;
 	default: // Unknown, try puck
@@ -444,13 +449,13 @@ mares_puck_extract_dives (device_t *abstract, const unsigned char data[], unsign
 
 	const mares_common_layout_t *layout = NULL;
 	switch (data[1]) {
-	case 1: // Nemo Wide
+	case NEMOWIDE:
 		layout = &mares_nemowide_layout;
 		break;
-	case 4: // Nemo Air
+	case NEMOAIR:
 		layout = &mares_nemoair_layout;
 		break;
-	case 7: // Puck
+	case PUCK:
 		layout = &mares_puck_layout;
 		break;
 	default: // Unknown, try puck