diff --git a/c/mapping/mapper_join.c b/c/mapping/mapper_join.c
index 924fa356e..2e76aac19 100644
--- a/c/mapping/mapper_join.c
+++ b/c/mapping/mapper_join.c
@@ -91,6 +91,7 @@ static sllv_t* mapper_join_process_sorted(lrec_t* pright_rec, context_t* pctx, v
 		}
 		sllv_free(pbucket_left_unpaired);
 		sllv_add(pout_recs, NULL);
+		return pout_recs;
 	}
 
 	slls_t* pright_field_values = mlr_selected_values_from_record(pright_rec, pstate->popts->pright_field_names);
diff --git a/c/test/expected/out b/c/test/expected/out
index 6b2559a34..45fa7b779 100644
--- a/c/test/expected/out
+++ b/c/test/expected/out
@@ -390,52 +390,265 @@ a=zee,b=pan,i=6,x=0.5271261600918548,y=0.49322128674835697
 ================================================================
 JOIN
 
-./test/../mlr join -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
-o=1,x=a,y=s
-o=2,x=b,y=t
-o=2,x=c,y=t
-o=2,x=d,y=t
-o=2,x=b,y=v
-o=2,x=c,y=v
-o=2,x=d,y=v
-o=3,x=e,y=w
-o=3,x=f,y=w
-o=3,x=e,y=x
-o=3,x=f,y=x
-o=3,x=e,y=y
-o=3,x=f,y=y
+./test/../mlr --opprint join -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
 
-./test/../mlr join --ul -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
-o=1,x=a,y=s
-o=2,x=b,y=t
-o=2,x=c,y=t
-o=2,x=d,y=t
-o=2,x=b,y=v
-o=2,x=c,y=v
-o=2,x=d,y=v
-o=3,x=e,y=w
-o=3,x=f,y=w
-o=3,x=e,y=x
-o=3,x=f,y=x
-o=3,x=e,y=y
-o=3,x=f,y=y
-l=4,x=g
+./test/../mlr --opprint join --ul -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
 
-./test/../mlr join --ur -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
-o=1,x=a,y=s
-o=2,x=b,y=t
-o=2,x=c,y=t
-o=2,x=d,y=t
-o=2,x=b,y=v
-o=2,x=c,y=v
-o=2,x=d,y=v
-o=3,x=e,y=w
-o=3,x=f,y=w
-o=3,x=e,y=x
-o=3,x=f,y=x
-o=3,x=e,y=y
-o=3,x=f,y=y
-r=5,y=z
+l x
+4 g
+
+./test/../mlr --opprint join --ur -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+r y
+5 z
+
+./test/../mlr --opprint join -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+./test/../mlr --opprint join --ul -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+l x
+4 g
+
+./test/../mlr --opprint join --ur -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+r y
+5 z
+
+./test/../mlr --opprint join --ul --ur -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+l x
+4 g
+
+r y
+5 z
+
+./test/../mlr --opprint join -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+./test/../mlr --opprint join --ul -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+l x
+4 g
+
+./test/../mlr --opprint join --ur -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+r y
+5 z
+
+./test/../mlr --opprint join -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+./test/../mlr --opprint join --ul -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+l x
+4 g
+
+./test/../mlr --opprint join --ur -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+r y
+5 z
+
+./test/../mlr --opprint join --ul --ur -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+r y
+5 z
+
+l x
+4 g
 
 
 ================================================================
diff --git a/c/test/output/out b/c/test/output/out
index 6b2559a34..45fa7b779 100644
--- a/c/test/output/out
+++ b/c/test/output/out
@@ -390,52 +390,265 @@ a=zee,b=pan,i=6,x=0.5271261600918548,y=0.49322128674835697
 ================================================================
 JOIN
 
-./test/../mlr join -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
-o=1,x=a,y=s
-o=2,x=b,y=t
-o=2,x=c,y=t
-o=2,x=d,y=t
-o=2,x=b,y=v
-o=2,x=c,y=v
-o=2,x=d,y=v
-o=3,x=e,y=w
-o=3,x=f,y=w
-o=3,x=e,y=x
-o=3,x=f,y=x
-o=3,x=e,y=y
-o=3,x=f,y=y
+./test/../mlr --opprint join -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
 
-./test/../mlr join --ul -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
-o=1,x=a,y=s
-o=2,x=b,y=t
-o=2,x=c,y=t
-o=2,x=d,y=t
-o=2,x=b,y=v
-o=2,x=c,y=v
-o=2,x=d,y=v
-o=3,x=e,y=w
-o=3,x=f,y=w
-o=3,x=e,y=x
-o=3,x=f,y=x
-o=3,x=e,y=y
-o=3,x=f,y=y
-l=4,x=g
+./test/../mlr --opprint join --ul -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
 
-./test/../mlr join --ur -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
-o=1,x=a,y=s
-o=2,x=b,y=t
-o=2,x=c,y=t
-o=2,x=d,y=t
-o=2,x=b,y=v
-o=2,x=c,y=v
-o=2,x=d,y=v
-o=3,x=e,y=w
-o=3,x=f,y=w
-o=3,x=e,y=x
-o=3,x=f,y=x
-o=3,x=e,y=y
-o=3,x=f,y=y
-r=5,y=z
+l x
+4 g
+
+./test/../mlr --opprint join --ur -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+r y
+5 z
+
+./test/../mlr --opprint join -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+./test/../mlr --opprint join --ul -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+l x
+4 g
+
+./test/../mlr --opprint join --ur -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+r y
+5 z
+
+./test/../mlr --opprint join --ul --ur -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+l x
+4 g
+
+r y
+5 z
+
+./test/../mlr --opprint join -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+./test/../mlr --opprint join --ul -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+l x
+4 g
+
+./test/../mlr --opprint join --ur -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+r y
+5 z
+
+./test/../mlr --opprint join -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+./test/../mlr --opprint join --ul -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+l x
+4 g
+
+./test/../mlr --opprint join --ur -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+r y
+5 z
+
+./test/../mlr --opprint join --ul --ur -u -f ./test/input/joina.dkvp -l l -r r -j o ./test/input/joinb.dkvp
+o x y
+1 a s
+2 b t
+2 c t
+2 d t
+2 b v
+2 c v
+2 d v
+3 e w
+3 f w
+3 e x
+3 f x
+3 e y
+3 f y
+
+r y
+5 z
+
+l x
+4 g
 
 
 ================================================================
diff --git a/c/test/run b/c/test/run
index 880b6e401..510ed8092 100755
--- a/c/test/run
+++ b/c/test/run
@@ -101,9 +101,21 @@ run_command $mlr sort -f a -r b -nf x -nr y $indir/abixy
 # ----------------------------------------------------------------
 announce JOIN
 
-run_command $mlr join      -u -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
-run_command $mlr join --ul -u -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
-run_command $mlr join --ur -u -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
+run_command $mlr --opprint join           -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
+run_command $mlr --opprint join --ul      -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
+run_command $mlr --opprint join --ur      -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
+run_command $mlr --opprint join           -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
+run_command $mlr --opprint join --ul      -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
+run_command $mlr --opprint join      --ur -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
+run_command $mlr --opprint join --ul --ur -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
+
+run_command $mlr --opprint join           -u -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
+run_command $mlr --opprint join --ul      -u -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
+run_command $mlr --opprint join --ur      -u -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
+run_command $mlr --opprint join           -u -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
+run_command $mlr --opprint join --ul      -u -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
+run_command $mlr --opprint join      --ur -u -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
+run_command $mlr --opprint join --ul --ur -u -f $indir/joina.dkvp -l l -r r -j o $indir/joinb.dkvp
 
 # ----------------------------------------------------------------
 announce STATS