diff --git a/common/include/villas/buffer.hpp b/common/include/villas/buffer.hpp
index ff7b1e4c6..7792cf8f3 100644
--- a/common/include/villas/buffer.hpp
+++ b/common/include/villas/buffer.hpp
@@ -48,7 +48,7 @@ public:
 
 	int parseJson(json_t **j);
 
-	int appendJson(json_t *j);
+	int appendJson(json_t *j, int flags = JSON_INDENT(4));
 };
 
 } /* namespace villas */
diff --git a/common/include/villas/json_buffer.hpp b/common/include/villas/json_buffer.hpp
index 484c6cf91..260afab14 100644
--- a/common/include/villas/json_buffer.hpp
+++ b/common/include/villas/json_buffer.hpp
@@ -39,7 +39,7 @@ protected:
 
 public:
 	/** Encode JSON document /p j and append it to the buffer */
-	int encode(json_t *j);
+	int encode(json_t *j, int flags = JSON_INDENT(4));
 
 	/** Decode JSON document from the beginning of the buffer */
 	json_t * decode();
diff --git a/common/lib/buffer.cpp b/common/lib/buffer.cpp
index f2d5c6a07..8fbd39622 100644
--- a/common/lib/buffer.cpp
+++ b/common/lib/buffer.cpp
@@ -75,11 +75,11 @@ int Buffer::parseJson(json_t **j)
 	return 0;
 }
 
-int Buffer::appendJson(json_t *j)
+int Buffer::appendJson(json_t *j, int flags)
 {
 	size_t l;
 
-retry:	l = json_dumpb(j, buf + len, size - len, 0);
+retry:	l = json_dumpb(j, buf + len, size - len, flags);
 	if (size < len + l) {
 		buf = (char *) realloc(buf, len + l);
 		if (!buf)
diff --git a/common/lib/json_buffer.cpp b/common/lib/json_buffer.cpp
index 83939c6e7..e3f521955 100644
--- a/common/lib/json_buffer.cpp
+++ b/common/lib/json_buffer.cpp
@@ -40,9 +40,9 @@ json_t * JsonBuffer::decode()
 	return j;
 }
 
-int JsonBuffer::encode(json_t *j)
+int JsonBuffer::encode(json_t *j, int flags)
 {
-	return json_dump_callback(j, callback, this, 0);
+	return json_dump_callback(j, callback, this, flags);
 }
 
 int JsonBuffer::callback(const char *data, size_t len, void *ctx)