diff --git a/src/apt.h b/src/apt.h
index 16aded7..e1429df 100644
--- a/src/apt.h
+++ b/src/apt.h
@@ -41,13 +41,17 @@ extern "C" {
 
 // Maximum height of an APT image in number of scanlines
 #define APT_MAX_HEIGHT 3000
+// Width in pixels of sync
 #define APT_SYNC_WIDTH 39
+// Width in pixels of space
 #define APT_SPC_WIDTH  47
+// Width in pixels of telemetry
 #define APT_TELE_WIDTH 45
 // Width in pixels of a single channel image
 #define APT_CH_WIDTH   909
 #define APT_FRAME_LEN  128
 #define APT_CH_OFFSET  (APT_SYNC_WIDTH+APT_SPC_WIDTH+APT_CH_WIDTH+APT_TELE_WIDTH)
+// Width in pixels of full frame, including sync, space, images and telemetry
 #define APT_IMG_WIDTH  2080
 // Offset in pixels to channel A
 #define APT_CHA_OFFSET (APT_SYNC_WIDTH+APT_SPC_WIDTH)
@@ -55,6 +59,9 @@ extern "C" {
 #define APT_CHB_OFFSET (APT_SYNC_WIDTH+APT_SPC_WIDTH+APT_CH_WIDTH+APT_TELE_WIDTH+APT_SYNC_WIDTH+APT_SPC_WIDTH)
 #define APT_TOTAL_TELE (APT_SYNC_WIDTH+APT_SPC_WIDTH+APT_TELE_WIDTH+APT_SYNC_WIDTH+APT_SPC_WIDTH+APT_TELE_WIDTH)
 
+// Width in elements of apt_image_t.prow arrays
+#define APT_PROW_WIDTH 2150
+
 // apt_getpixelrow callback function to get audio samples.
 // context is the same as passed to apt_getpixelrow.
 typedef int (*apt_getsamples_t)(void *context, float *samples, int count);
diff --git a/src/image.c b/src/image.c
index 7c1fb5d..712cc17 100644
--- a/src/image.c
+++ b/src/image.c
@@ -318,7 +318,7 @@ int apt_cropNoise(apt_image_t *img){
 
 	// Remove the noisy rows at start
 	for(int y = 0; y < img->nrow-startCrop; y++) {
-		memmove(img->prow[y], img->prow[y+startCrop], sizeof(float)*2150);
+		memmove(img->prow[y], img->prow[y+startCrop], sizeof(float)*APT_PROW_WIDTH);
 	}
 
 	// Ignore the noisy rows at the end
diff --git a/src/main.c b/src/main.c
index 0932587..677487d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -161,7 +161,7 @@ static int processAudio(char *filename, options_t *opts){
 		// TODO: multithreading, would require some sort of input buffer
 		for (img.nrow = 0; img.nrow < APT_MAX_HEIGHT; img.nrow++) {
 			// Allocate memory for this row
-			img.prow[img.nrow] = (float *) malloc(sizeof(float) * 2150);
+			img.prow[img.nrow] = (float *) malloc(sizeof(float) * APT_PROW_WIDTH);
 
 			// Write into memory and break the loop when there are no more samples to read
 			if (apt_getpixelrow(img.prow[img.nrow], img.nrow, &img.zenith, (img.nrow == 0), getsamples, NULL) == 0)
@@ -216,8 +216,8 @@ static int processAudio(char *filename, options_t *opts){
 		// Create another buffer as to not modify the orignal
 		apt_image_t tmpimg = img;
 		for(int i = 0; i < img.nrow; i++){
-			tmpimg.prow[i] = (float *) malloc(sizeof(float) * 2150);
-			memcpy(tmpimg.prow[i], img.prow[i], sizeof(float) * 2150);
+			tmpimg.prow[i] = (float *) malloc(sizeof(float) * APT_PROW_WIDTH);
+			memcpy(tmpimg.prow[i], img.prow[i], sizeof(float) * APT_PROW_WIDTH);
 		}
 
 		// Perform temperature calibration