diff --git a/include/proto/sample.h b/include/proto/sample.h
index b8a10400f..db703ef20 100644
--- a/include/proto/sample.h
+++ b/include/proto/sample.h
@@ -42,6 +42,7 @@ const char *sample_ckp_names(unsigned int use);
 struct sample_fetch *find_sample_fetch(const char *kw, int len);
 int smp_resolve_args(struct proxy *p);
 int smp_expr_output_type(struct sample_expr *expr);
+int c_none(struct sample *smp);
 
 /*
  * This function just apply a cast on sample. It returns 0 if the cast is not
@@ -53,6 +54,8 @@ int sample_convert(struct sample *sample, int req_type)
 {
 	if (!sample_casts[sample->type][req_type])
 		return 0;
+	if (sample_casts[sample->type][req_type] == c_none)
+		return 1;
 	return sample_casts[sample->type][req_type](sample);
 }
 
diff --git a/src/sample.c b/src/sample.c
index f57811e5a..7568d270e 100644
--- a/src/sample.c
+++ b/src/sample.c
@@ -559,7 +559,7 @@ static int c_bindup(struct sample *smp)
 }
 
 
-static int c_none(struct sample *smp)
+int c_none(struct sample *smp)
 {
 	return 1;
 }