diff --git a/include/common/standard.h b/include/common/standard.h
index 0fe0fb08b..357d22cfd 100644
--- a/include/common/standard.h
+++ b/include/common/standard.h
@@ -388,25 +388,34 @@ char *encode_chunk(char *start, char *stop,
  * the input string is null-terminated.
  *
  * If <quote> is 0, the result is returned escaped but without double quote.
- * Is it useful if the escaped string is used between double quotes in the
+ * It is useful if the escaped string is used between double quotes in the
  * format.
  *
- *    printf("..., \"%s\", ...\r\n", csv_enc(str, 0));
+ *    printf("..., \"%s\", ...\r\n", csv_enc(str, 0, &trash));
  *
- * If the <quote> is 1, the converter put the quotes only if any character is
- * escaped. If the <quote> is 2, the converter put always the quotes.
+ * If <quote> is 1, the converter puts the quotes only if any character is
+ * escaped. If <quote> is 2, the converter always puts the quotes.
  *
- * <output> is a struct chunk used for storing the output string if any
- * change will be done.
+ * <output> is a struct chunk used for storing the output string.
  *
- * The function returns the converted string on this output. If an error
- * occurs, the function return an empty string. This type of output is useful
+ * The function returns the converted string on its output. If an error
+ * occurs, the function returns an empty string. This type of output is useful
  * for using the function directly as printf() argument.
  *
- * If the output buffer is too short to conatin the input string, the result
+ * If the output buffer is too short to contain the input string, the result
  * is truncated.
+ *
+ * This function appends the encoding to the existing output chunk. Please
+ * use csv_enc() instead if you want to replace the output chunk.
  */
-const char *csv_enc(const char *str, int quote, struct chunk *output);
+const char *csv_enc_append(const char *str, int quote, struct chunk *output);
+
+/* same as above but the output chunk is reset first */
+static inline const char *csv_enc(const char *str, int quote, struct chunk *output)
+{
+	chunk_reset(output);
+	return csv_enc_append(str, quote, output);
+}
 
 /* Decode an URL-encoded string in-place. The resulting string might
  * be shorter. If some forbidden characters are found, the conversion is
diff --git a/src/standard.c b/src/standard.c
index 969daf6b3..adbffd4c4 100644
--- a/src/standard.c
+++ b/src/standard.c
@@ -1438,61 +1438,62 @@ char *encode_chunk(char *start, char *stop,
  * the input string is null-terminated.
  *
  * If <quote> is 0, the result is returned escaped but without double quote.
- * Is it useful if the escaped string is used between double quotes in the
+ * It is useful if the escaped string is used between double quotes in the
  * format.
  *
- *    printf("..., \"%s\", ...\r\n", csv_enc(str, 0));
+ *    printf("..., \"%s\", ...\r\n", csv_enc(str, 0, &trash));
  *
- * If the <quote> is 1, the converter put the quotes only if any character is
- * escaped. If the <quote> is 2, the converter put always the quotes.
+ * If <quote> is 1, the converter puts the quotes only if any character is
+ * escaped. If <quote> is 2, the converter always puts the quotes.
  *
- * <output> is a struct chunk used for storing the output string if any
- * change will be done.
+ * <output> is a struct chunk used for storing the output string.
  *
- * The function returns the converted string on this output. If an error
- * occurs, the function return an empty string. This type of output is useful
+ * The function returns the converted string on its output. If an error
+ * occurs, the function returns an empty string. This type of output is useful
  * for using the function directly as printf() argument.
  *
  * If the output buffer is too short to contain the input string, the result
  * is truncated.
+ *
+ * This function appends the encoding to the existing output chunk. Please
+ * use csv_enc() instead if you want to replace the output chunk.
  */
-const char *csv_enc(const char *str, int quote, struct chunk *output)
+const char *csv_enc_append(const char *str, int quote, struct chunk *output)
 {
 	char *end = output->str + output->size;
-	char *out = output->str + 1; /* +1 for reserving space for a first <"> */
+	char *out = output->str + output->len + 1; /* +1 for reserving space for a first <"> */
+	char *ptr = out;
 
-	while (*str && out < end - 2) { /* -2 for reserving space for <"> and \0. */
-		*out = *str;
+	while (*str && ptr < end - 2) { /* -2 for reserving space for <"> and \0. */
+		*ptr = *str;
 		if (*str == '"') {
 			if (quote == 1)
 				quote = 2;
-			out++;
-			if (out >= end - 2) {
-				out--;
+			ptr++;
+			if (ptr >= end - 2) {
+				ptr--;
 				break;
 			}
-			*out = '"';
+			*ptr = '"';
 		}
 		if (quote == 1 && ( *str == '\r' || *str == '\n' || *str == ',') )
 			quote = 2;
-		out++;
+		ptr++;
 		str++;
 	}
 
-	if (quote == 1)
-		quote = 0;
-
-	if (!quote) {
-		*out = '\0';
-		return output->str + 1;
+	if (quote < 2) {
+		*ptr = '\0';
+		output->len = ptr - output->str;
+		return out;
 	}
 
-	/* else quote == 2 */
-	*output->str = '"';
-	*out = '"';
-	out++;
-	*out = '\0';
-	return output->str;
+	/* quote == 2 : add quotes */
+	*--out = '"';
+	*++ptr = '"';
+	*ptr = '\0';
+	output->len = ptr - output->str;
+	return out;
 }
 
 /* Decode an URL-encoded string in-place. The resulting string might