diff --git a/include/proto/protocol_buffers.h b/include/proto/protocol_buffers.h
index 97f9bf55a..a9deab129 100644
--- a/include/proto/protocol_buffers.h
+++ b/include/proto/protocol_buffers.h
@@ -23,6 +23,7 @@
 #define _PROTO_PROTOCOL_BUFFERS_H
 
 #include <stdint.h>
+#include <types/arg.h>
 #include <types/protocol_buffers.h>
 #include <proto/sample.h>
 
@@ -477,6 +478,95 @@ int protobuf_smp_store_32bit(struct sample *smp, int type,
 	return 1;
 }
 
+/*
+ * Lookup for a protocol buffers field whose parameters are provided by <arg_p>
+ * first argument in the buffer with <pos> as address and <len> as length address.
+ * If found, store its value depending on the type of storage to use provided by <arg_p>
+ * second argument and return 1, 0 if not.
+ */
+static inline int protobuf_field_lookup(const struct arg *arg_p, struct sample *smp,
+                                        unsigned char **pos, size_t *len)
+{
+	unsigned int *fid;
+	size_t fid_sz;
+	int type;
+	uint64_t elen;
+	int field;
+
+	fid = arg_p[0].data.fid.ids;
+	fid_sz = arg_p[0].data.fid.sz;
+	type = arg_p[1].data.sint;
+
+	/* Length of the length-delimited messages if any. */
+	elen = 0;
+	field = 0;
+
+	while (field < fid_sz) {
+		int found;
+		uint64_t key, sleft;
+		struct protobuf_parser_def *pbuf_parser = NULL;
+		unsigned int wire_type, field_number;
+
+		if ((ssize_t)*len <= 0)
+			return 0;
+
+		/* Remaining bytes saving. */
+		sleft = *len;
+
+		/* Key decoding */
+		if (!protobuf_decode_varint(&key, pos, len))
+			return 0;
+
+		wire_type = key & 0x7;
+		field_number = key >> 3;
+		found = field_number == fid[field];
+
+		/* Skip the data if the current field does not match. */
+		switch (wire_type) {
+		case PBUF_TYPE_VARINT:
+		case PBUF_TYPE_32BIT:
+		case PBUF_TYPE_64BIT:
+			pbuf_parser = &protobuf_parser_defs[wire_type];
+			if (!found && !pbuf_parser->skip(pos, len, 0))
+				return 0;
+			break;
+
+		case PBUF_TYPE_LENGTH_DELIMITED:
+			/* Decode the length of this length-delimited field. */
+			if (!protobuf_decode_varint(&elen, pos, len) || elen > *len)
+				return 0;
+
+			/* The size of the current field is computed from here to skip
+			 * the bytes used to encode the previous length.*
+			 */
+			sleft = *len;
+			pbuf_parser = &protobuf_parser_defs[wire_type];
+			if (!found && !pbuf_parser->skip(pos, len, elen))
+				return 0;
+			break;
+
+		default:
+			return 0;
+		}
+
+		/* Store the data if found. Note that <pbuf_parser> is not NULL */
+		if (found && field == fid_sz - 1)
+			return pbuf_parser->smp_store(smp, type, *pos, *len, elen);
+
+		if ((ssize_t)(elen) > 0)
+			elen -= sleft - *len;
+
+		if (found) {
+			field++;
+		}
+		else if ((ssize_t)elen <= 0) {
+			field = 0;
+		}
+	}
+
+	return 0;
+}
+
 #endif /* _PROTO_PROTOCOL_BUFFERS_H */
 
 /*
diff --git a/src/sample.c b/src/sample.c
index 5b0ccc953..e95c57c10 100644
--- a/src/sample.c
+++ b/src/sample.c
@@ -2763,26 +2763,12 @@ static int sample_conv_ungrpc(const struct arg *arg_p, struct sample *smp, void
 {
 	unsigned char *pos;
 	size_t grpc_left;
-	unsigned int *fid;
-	size_t fid_sz;
-	int type;
-
-	if (!smp->strm)
-		return 0;
-
-	fid = arg_p[0].data.fid.ids;
-	fid_sz = arg_p[0].data.fid.sz;
-	type = arg_p[1].data.sint;
 
 	pos = (unsigned char *)smp->data.u.str.area;
-	/* Remaining bytes in the body to be parsed. */
 	grpc_left = smp->data.u.str.data;
 
 	while (grpc_left > GRPC_MSG_HEADER_SZ) {
-		int field, found;
 		size_t grpc_msg_len, left;
-		unsigned int wire_type, field_number;
-		uint64_t key, elen;
 
 		grpc_msg_len = left = ntohl(*(uint32_t *)(pos + GRPC_MSG_COMPRESS_FLAG_SZ));
 
@@ -2792,92 +2778,9 @@ static int sample_conv_ungrpc(const struct arg *arg_p, struct sample *smp, void
 		if (grpc_left < left)
 			return 0;
 
-		found = 1;
-		/* Length of the length-delimited messages if any. */
-		elen = 0;
+		if (protobuf_field_lookup(arg_p, smp, &pos, &left))
+			return 1;
 
-		/* Message decoding: there may be serveral key+value protobuf pairs by
-		 * gRPC message.
-		 */
-		field = 0;
-		while (field < fid_sz) {
-			uint64_t sleft;
-
-			if ((ssize_t)left <= 0)
-				return 0;
-
-			/* Remaining bytes saving. */
-			sleft = left;
-
-			/* Key decoding */
-			if (!protobuf_decode_varint(&key, &pos, &left))
-				return 0;
-
-			wire_type = key & 0x7;
-			field_number = key >> 3;
-			found = field_number == fid[field];
-
-			switch (wire_type) {
-			case PBUF_TYPE_VARINT:
-			case PBUF_TYPE_32BIT:
-			case PBUF_TYPE_64BIT:
-			{
-				struct protobuf_parser_def *pbuf_parser;
-
-				pbuf_parser = &protobuf_parser_defs[wire_type];
-				if (!found) {
-					/* Skip the data. */
-					if (!pbuf_parser->skip(&pos, &left, 0))
-						return 0;
-				}
-				else if (field == fid_sz - 1) {
-					return pbuf_parser->smp_store(smp, type, pos, left, 0);
-				}
-
-				break;
-			}
-
-			case PBUF_TYPE_LENGTH_DELIMITED:
-			{
-				struct protobuf_parser_def *pbuf_parser;
-
-				/* Decode the length of this length-delimited field. */
-				if (!protobuf_decode_varint(&elen, &pos, &left))
-					return 0;
-
-				if (elen > left)
-					return 0;
-
-				/* The size of the current field is computed from here do skip
-				 * the bytes to encode the previous lenght.*
-				 */
-				sleft = left;
-				pbuf_parser = &protobuf_parser_defs[wire_type];
-				if (!found) {
-					/* Skip the data. */
-					if (!pbuf_parser->skip(&pos, &left, elen))
-						return 0;
-				} else if (field == fid_sz - 1) {
-					return pbuf_parser->smp_store(smp, type, pos, left, elen);
-				}
-
-				break;
-			}
-
-			default:
-				return 0;
-			}
-
-			if ((ssize_t)(elen) > 0)
-				elen -= sleft - left;
-
-			if (found) {
-				field++;
-			}
-			else if ((ssize_t)elen <= 0) {
-				field = 0;
-			}
-		}
 		grpc_left -= grpc_msg_len;
 	}