diff --git a/c/reg_test/expected/out b/c/reg_test/expected/out
index 7687117e5..c77079127 100644
--- a/c/reg_test/expected/out
+++ b/c/reg_test/expected/out
@@ -1091,6 +1091,172 @@ a=zee,b=wye,i=8,x=0.5985540091064224,y=0.976181385699006
 a=pan,b=wye,i=10,x=0.5026260055412137,y=0.9526183602969864
 
 
+================================================================
+WHITESPACE-REDUCTION
+
+mlr --icsv --ojson cat ./reg_test/input/clean-whitespace.csv
+{ "n": 1, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 2, "a": "xy ", "b  ": 2, "  c": 3 }
+{ "n": 3, "a": "xy  ", "b  ": 2, "  c": 3 }
+{ "n": 4, "a": "xy   ", "b  ": 2, "  c": 3 }
+{ "n": 5, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 6, "a": " xy", "b  ": 2, "  c": 3 }
+{ "n": 7, "a": "  xy", "b  ": 2, "  c": 3 }
+{ "n": 8, "a": "   xy", "b  ": 2, "  c": 3 }
+{ "n": 9, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 10, "a": " xy ", "b  ": 2, "  c": 3 }
+{ "n": 11, "a": "  xy  ", "b  ": 2, "  c": 3 }
+{ "n": 12, "a": "   xy   ", "b  ": 2, "  c": 3 }
+{ "n": 13, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 14, "a": "  ", "b  ": 2, "  c": 3 }
+{ "n": 15, "a": "    ", "b  ": 2, "  c": 3 }
+{ "n": 16, "a": "      ", "b  ": 2, "  c": 3 }
+
+mlr --icsv --ojson put $a = lstrip($a) ./reg_test/input/clean-whitespace.csv
+{ "n": 1, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 2, "a": "xy ", "b  ": 2, "  c": 3 }
+{ "n": 3, "a": "xy  ", "b  ": 2, "  c": 3 }
+{ "n": 4, "a": "xy   ", "b  ": 2, "  c": 3 }
+{ "n": 5, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 6, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 7, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 8, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 9, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 10, "a": "xy ", "b  ": 2, "  c": 3 }
+{ "n": 11, "a": "xy  ", "b  ": 2, "  c": 3 }
+{ "n": 12, "a": "xy   ", "b  ": 2, "  c": 3 }
+{ "n": 13, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 14, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 15, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 16, "a": "", "b  ": 2, "  c": 3 }
+
+mlr --icsv --ojson put $a = rstrip($a) ./reg_test/input/clean-whitespace.csv
+{ "n": 1, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 2, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 3, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 4, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 5, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 6, "a": " xy", "b  ": 2, "  c": 3 }
+{ "n": 7, "a": "  xy", "b  ": 2, "  c": 3 }
+{ "n": 8, "a": "   xy", "b  ": 2, "  c": 3 }
+{ "n": 9, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 10, "a": " xy", "b  ": 2, "  c": 3 }
+{ "n": 11, "a": "  xy", "b  ": 2, "  c": 3 }
+{ "n": 12, "a": "   xy", "b  ": 2, "  c": 3 }
+{ "n": 13, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 14, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 15, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 16, "a": "", "b  ": 2, "  c": 3 }
+
+mlr --icsv --ojson put $a = strip($a) ./reg_test/input/clean-whitespace.csv
+{ "n": 1, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 2, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 3, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 4, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 5, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 6, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 7, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 8, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 9, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 10, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 11, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 12, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 13, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 14, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 15, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 16, "a": "", "b  ": 2, "  c": 3 }
+
+mlr --icsv --ojson put $a = collapse_whitespace($a) ./reg_test/input/clean-whitespace.csv
+{ "n": 1, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 2, "a": "xy ", "b  ": 2, "  c": 3 }
+{ "n": 3, "a": "xy ", "b  ": 2, "  c": 3 }
+{ "n": 4, "a": "xy ", "b  ": 2, "  c": 3 }
+{ "n": 5, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 6, "a": " xy", "b  ": 2, "  c": 3 }
+{ "n": 7, "a": " xy", "b  ": 2, "  c": 3 }
+{ "n": 8, "a": " xy", "b  ": 2, "  c": 3 }
+{ "n": 9, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 10, "a": " xy ", "b  ": 2, "  c": 3 }
+{ "n": 11, "a": " xy ", "b  ": 2, "  c": 3 }
+{ "n": 12, "a": " xy ", "b  ": 2, "  c": 3 }
+{ "n": 13, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 14, "a": " ", "b  ": 2, "  c": 3 }
+{ "n": 15, "a": " ", "b  ": 2, "  c": 3 }
+{ "n": 16, "a": " ", "b  ": 2, "  c": 3 }
+
+mlr --icsv --ojson put $a = clean_whitespace($a) ./reg_test/input/clean-whitespace.csv
+{ "n": 1, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 2, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 3, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 4, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 5, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 6, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 7, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 8, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 9, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 10, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 11, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 12, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 13, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 14, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 15, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 16, "a": "", "b  ": 2, "  c": 3 }
+
+mlr --icsv --ojson clean-whitespace -k ./reg_test/input/clean-whitespace.csv
+{ "n": 1, "a": "xy", "b": 2, "c": 3 }
+{ "n": 2, "a": "xy ", "b": 2, "c": 3 }
+{ "n": 3, "a": "xy  ", "b": 2, "c": 3 }
+{ "n": 4, "a": "xy   ", "b": 2, "c": 3 }
+{ "n": 5, "a": "xy", "b": 2, "c": 3 }
+{ "n": 6, "a": " xy", "b": 2, "c": 3 }
+{ "n": 7, "a": "  xy", "b": 2, "c": 3 }
+{ "n": 8, "a": "   xy", "b": 2, "c": 3 }
+{ "n": 9, "a": "xy", "b": 2, "c": 3 }
+{ "n": 10, "a": " xy ", "b": 2, "c": 3 }
+{ "n": 11, "a": "  xy  ", "b": 2, "c": 3 }
+{ "n": 12, "a": "   xy   ", "b": 2, "c": 3 }
+{ "n": 13, "a": "", "b": 2, "c": 3 }
+{ "n": 14, "a": "  ", "b": 2, "c": 3 }
+{ "n": 15, "a": "    ", "b": 2, "c": 3 }
+{ "n": 16, "a": "      ", "b": 2, "c": 3 }
+
+mlr --icsv --ojson clean-whitespace -v ./reg_test/input/clean-whitespace.csv
+{ "n": 1, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 2, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 3, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 4, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 5, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 6, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 7, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 8, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 9, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 10, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 11, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 12, "a": "xy", "b  ": 2, "  c": 3 }
+{ "n": 13, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 14, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 15, "a": "", "b  ": 2, "  c": 3 }
+{ "n": 16, "a": "", "b  ": 2, "  c": 3 }
+
+mlr --icsv --ojson clean-whitespace ./reg_test/input/clean-whitespace.csv
+{ "n": 1, "a": "xy", "b": 2, "c": 3 }
+{ "n": 2, "a": "xy", "b": 2, "c": 3 }
+{ "n": 3, "a": "xy", "b": 2, "c": 3 }
+{ "n": 4, "a": "xy", "b": 2, "c": 3 }
+{ "n": 5, "a": "xy", "b": 2, "c": 3 }
+{ "n": 6, "a": "xy", "b": 2, "c": 3 }
+{ "n": 7, "a": "xy", "b": 2, "c": 3 }
+{ "n": 8, "a": "xy", "b": 2, "c": 3 }
+{ "n": 9, "a": "xy", "b": 2, "c": 3 }
+{ "n": 10, "a": "xy", "b": 2, "c": 3 }
+{ "n": 11, "a": "xy", "b": 2, "c": 3 }
+{ "n": 12, "a": "xy", "b": 2, "c": 3 }
+{ "n": 13, "a": "", "b": 2, "c": 3 }
+{ "n": 14, "a": "", "b": 2, "c": 3 }
+{ "n": 15, "a": "", "b": 2, "c": 3 }
+{ "n": 16, "a": "", "b": 2, "c": 3 }
+
+
 ================================================================
 SORT
 
diff --git a/c/reg_test/input/Makefile.am b/c/reg_test/input/Makefile.am
index 2b7ff0d5e..dce594e81 100644
--- a/c/reg_test/input/Makefile.am
+++ b/c/reg_test/input/Makefile.am
@@ -27,6 +27,7 @@ EXTRA_DIST=	\
 		c.pprint \
 		capture-lengths.dkvp \
 		capture.dkvp \
+		clean-whitespace.csv \
 		comments \
 		d.csv \
 		d.pprint \
diff --git a/c/reg_test/input/clean-whitespace.csv b/c/reg_test/input/clean-whitespace.csv
new file mode 100644
index 000000000..420c41b11
--- /dev/null
+++ b/c/reg_test/input/clean-whitespace.csv
@@ -0,0 +1,17 @@
+n,a,b  ,  c
+1,xy,2,3
+2,xy ,2,3
+3,xy  ,2,3
+4,xy   ,2,3
+5,xy,2,3
+6, xy,2,3
+7,  xy,2,3
+8,   xy,2,3
+9,xy,2,3
+10, xy ,2,3
+11,  xy  ,2,3
+12,   xy   ,2,3
+13,,2,3
+14,  ,2,3
+15,    ,2,3
+16,      ,2,3
diff --git a/c/reg_test/run b/c/reg_test/run
index 987ab7103..ff747f40b 100755
--- a/c/reg_test/run
+++ b/c/reg_test/run
@@ -337,6 +337,20 @@ run_mlr decimate -g a    -n 2 $indir/abixy
 run_mlr decimate -g a -b -n 2 $indir/abixy
 run_mlr decimate -g a -e -n 2 $indir/abixy
 
+# ----------------------------------------------------------------
+announce WHITESPACE-REDUCTION
+
+run_mlr --icsv --ojson cat                                $indir/clean-whitespace.csv
+run_mlr --icsv --ojson put '$a = lstrip($a)'              $indir/clean-whitespace.csv
+run_mlr --icsv --ojson put '$a = rstrip($a)'              $indir/clean-whitespace.csv
+run_mlr --icsv --ojson put '$a = strip($a)'               $indir/clean-whitespace.csv
+run_mlr --icsv --ojson put '$a = collapse_whitespace($a)' $indir/clean-whitespace.csv
+run_mlr --icsv --ojson put '$a = clean_whitespace($a)'    $indir/clean-whitespace.csv
+
+run_mlr --icsv --ojson clean-whitespace -k $indir/clean-whitespace.csv
+run_mlr --icsv --ojson clean-whitespace -v $indir/clean-whitespace.csv
+run_mlr --icsv --ojson clean-whitespace    $indir/clean-whitespace.csv
+
 # ----------------------------------------------------------------
 announce SORT