diff --git a/qrenc.c b/qrenc.c
index c09c4ab6..a937d7d9 100644
--- a/qrenc.c
+++ b/qrenc.c
@@ -733,19 +733,26 @@ static int writeXPM(const QRcode *qrcode, const char *outfile)
 	return 0;
 }
 
-static void writeANSI_margin(FILE* fp, int realwidth,
-                             char* buffer, const char* white, int white_s )
+static void writeANSI_margin(FILE* fp, size_t realwidth,
+                             char* buffer, const char* white, size_t white_s)
 {
 	int y;
 
-	strncpy(buffer, white, (size_t)white_s);
-	memset(buffer + white_s, ' ', (size_t)realwidth * 2);
+	strncpy(buffer, white, white_s);
+	memset(buffer + white_s, ' ', realwidth * 2);
 	strcpy(buffer + white_s + realwidth * 2, "\033[0m\n"); // reset to default colors
-	for(y = 0; y < margin; y++ ){
+	for (y = 0; y < margin; y++) {
 		fputs(buffer, fp);
 	}
 }
 
+#define COPY_AND_ADVANCE(BUF, STR)        \
+	do {                              \
+		strcpy(BUF, STR);         \
+		BUF += strlen(STR);       \
+	} while (0)
+
+
 static int writeANSI(const QRcode *qrcode, const char *outfile)
 {
 	FILE *fp;
@@ -756,29 +763,26 @@ static int writeANSI(const QRcode *qrcode, const char *outfile)
 
 	const char *white, *black;
 	char *buffer;
-	int white_s, black_s, buffer_s;
+	char *pbuf;
+	size_t white_s, black_s, buffer_s;
 
-	if(image_type == ANSI256_TYPE){
+	if (image_type == ANSI256_TYPE) {
 		/* codes for 256 color compatible terminals */
 		white = "\033[48;5;231m";
-		white_s = 11;
 		black = "\033[48;5;16m";
-		black_s = 10;
 	} else {
 		white = "\033[47m";
-		white_s = 5;
 		black = "\033[40m";
-		black_s = 5;
 	}
-
-	size = 1;
+	white_s = strlen(white);
+	black_s = strlen(black);
 
 	fp = openFile(outfile);
 
-	realwidth = (qrcode->width + margin * 2) * size;
-	buffer_s = (realwidth * white_s) * 2;
-	buffer = (char *)malloc((size_t)buffer_s);
-	if(buffer == NULL) {
+	realwidth = qrcode->width + margin * 2;
+	buffer_s = (realwidth * (white_s > black_s ? white_s : black_s)) * 2;
+	buffer = malloc(buffer_s);
+	if (buffer == NULL) {
 		fprintf(stderr, "Failed to allocate memory.\n");
 		exit(EXIT_FAILURE);
 	}
@@ -788,36 +792,37 @@ static int writeANSI(const QRcode *qrcode, const char *outfile)
 
 	/* data */
 	p = qrcode->data;
-	for(y = 0; y < qrcode->width; y++) {
-		row = (p+(y*qrcode->width));
+	for (y = 0; y < qrcode->width; y++) {
+		row = p + (y * qrcode->width);
 
-		memset(buffer, 0, (size_t)buffer_s);
-		strncpy(buffer, white, (size_t)white_s);
-		for(x = 0; x < margin; x++ ){
-			strncat(buffer, "  ", 2);
+		memset(buffer, 0, buffer_s);
+		pbuf = buffer;
+		COPY_AND_ADVANCE(pbuf, white);
+		for (x = 0; x < margin; x++) {
+			COPY_AND_ADVANCE(pbuf, "  ");
 		}
 		last = 0;
 
-		for(x = 0; x < qrcode->width; x++) {
-			if(*(row+x)&0x1) {
-				if( last != 1 ){
-					strncat(buffer, black, (size_t)black_s);
+		for (x = 0; x < qrcode->width; x++) {
+			if (row[x] & 0x1) {
+				if (last != 1) {
+					COPY_AND_ADVANCE(pbuf, black);
 					last = 1;
 				}
-			} else if( last != 0 ){
-				strncat(buffer, white, (size_t)white_s);
+			} else if(last != 0) {
+				COPY_AND_ADVANCE(pbuf, white);
 				last = 0;
 			}
-			strncat(buffer, "  ", 2);
+			COPY_AND_ADVANCE(pbuf, "  ");
 		}
 
-		if( last != 0 ){
-			strncat(buffer, white, (size_t)white_s);
+		if (last != 0) {
+			COPY_AND_ADVANCE(pbuf, white);
 		}
-		for(x = 0; x < margin; x++ ){
-			strncat(buffer, "  ", 2);
+		for (x = 0; x < margin; x++) {
+			COPY_AND_ADVANCE(pbuf, "  ");
 		}
-		strncat(buffer, "\033[0m\n", 5);
+		COPY_AND_ADVANCE(pbuf, "\033[0m\n");
 		fputs(buffer, fp);
 	}
 
@@ -959,8 +964,6 @@ static int writeASCII(const QRcode *qrcode, const char *outfile, int invert)
 		white = '#';
 	}
 
-	size = 1;
-
 	fp = openFile(outfile);
 
 	realwidth = (qrcode->width + margin * 2) * 2;