diff --git a/doc/bitstring/Makefile.am b/doc/bitstring/Makefile.am
index 259ab62..e9cbfe6 100644
--- a/doc/bitstring/Makefile.am
+++ b/doc/bitstring/Makefile.am
@@ -18,8 +18,8 @@ bitstring.html: bitstring.ms
 	(cat $?; echo ".Tc") | $(UNROFF) document=bitstring
 
 index.ms: bitstring.ms index.raw
-	sort -f -t'#' +1 -3 +0n index.raw | awk -f ../util/fixindex.awk\
-	    | awk -f ../util/block.awk >index.ms
+	sort -f -t'#' +1 -3 +0n index.raw | $(AWK) -f ../util/fixindex.awk\
+	    | $(AWK) -f ../util/block.awk >index.ms
 
 index.raw: bitstring.ms
 	$(TROFF) bitstring.ms 2> index.raw >/dev/null
diff --git a/doc/cprog/Makefile.am b/doc/cprog/Makefile.am
index 89f84a9..d3bf225 100644
--- a/doc/cprog/Makefile.am
+++ b/doc/cprog/Makefile.am
@@ -8,7 +8,7 @@ endif
 
 TROFF= groff -ms -t
 UNROFF= unroff -ms
-MKINDEX= awk -f ../util/mkindex.awk
+MKINDEX= $(AWK) -f ../util/mkindex.awk
 
 cprog.ps: cprog.ms side.ref side.inx
 	$(MKINDEX) cprog.ms | sed -f side.ref | $(TROFF) 2> /dev/null > $@
@@ -18,7 +18,7 @@ side.ref: side
 
 side.inx: side
 	egrep -v '^s' side | sort -f -t'#' +1 -3 +0n | \
-	    awk -f ../util/fixindex.awk | awk -f ../util/block.awk \
+	    $(AWK) -f ../util/fixindex.awk | $(AWK) -f ../util/block.awk \
 	    > side.inx
 
 side: cprog.ms
diff --git a/doc/kernel/Makefile.am b/doc/kernel/Makefile.am
index ab040b9..c650c4d 100644
--- a/doc/kernel/Makefile.am
+++ b/doc/kernel/Makefile.am
@@ -18,8 +18,8 @@ kernel.html: kernel.ms
 	(cat $?; echo ".Tc") | $(UNROFF) document=kernel
 
 index.ms: kernel.ms index.raw
-	sort -f -t'#' +1 -3 +0n index.raw | awk -f ../util/fixindex.awk\
-	    | awk -f ../util/block.awk >index.ms
+	sort -f -t'#' +1 -3 +0n index.raw | $(AWK) -f ../util/fixindex.awk\
+	    | $(AWK) -f ../util/block.awk >index.ms
 
 index.raw: kernel.ms
 	$(TROFF) kernel.ms 2> index.raw >/dev/null
diff --git a/doc/oops/Makefile.am b/doc/oops/Makefile.am
index a2b7401..dfdd001 100644
--- a/doc/oops/Makefile.am
+++ b/doc/oops/Makefile.am
@@ -18,8 +18,8 @@ oops.html: oops.ms
 	(cat $?; echo ".Tc") | $(UNROFF) document=oops
 
 index.ms: oops.ms index.raw
-	sort -f -t'#' +1 -3 +0n index.raw | awk -f ../util/fixindex.awk\
-	    | awk -f ../util/block.awk >index.ms
+	sort -f -t'#' +1 -3 +0n index.raw | $(AWK) -f ../util/fixindex.awk\
+	    | $(AWK) -f ../util/block.awk >index.ms
 
 index.raw: oops.ms
 	$(TROFF) oops.ms 2> index.raw >/dev/null
diff --git a/doc/record/Makefile.am b/doc/record/Makefile.am
index cbf992c..55bc9de 100644
--- a/doc/record/Makefile.am
+++ b/doc/record/Makefile.am
@@ -18,8 +18,8 @@ record.html: record.ms
 	(cat $?; echo ".Tc") | $(UNROFF) document=record
 
 index.ms: record.ms index.raw
-	sort -f -t'#' +1 -3 +0n index.raw | awk -f ../util/fixindex.awk\
-	    | awk -f ../util/block.awk >index.ms
+	sort -f -t'#' +1 -3 +0n index.raw | $(AWK) -f ../util/fixindex.awk\
+	    | $(AWK) -f ../util/block.awk >index.ms
 
 index.raw: record.ms
 	$(TROFF) record.ms 2> index.raw >/dev/null
diff --git a/doc/regexp/Makefile.am b/doc/regexp/Makefile.am
index 755aa05..7cc5a30 100644
--- a/doc/regexp/Makefile.am
+++ b/doc/regexp/Makefile.am
@@ -18,8 +18,8 @@ regexp.html: regexp.ms
 	(cat $?; echo ".Tc") | $(UNROFF) document=regexp
 
 index.ms: regexp.ms index.raw
-	sort -f -t'#' +1 -3 +0n index.raw | awk -f ../util/fixindex.awk\
-	    | awk -f ../util/block.awk >index.ms
+	sort -f -t'#' +1 -3 +0n index.raw | $(AWK) -f ../util/fixindex.awk\
+	    | $(AWK) -f ../util/block.awk >index.ms
 
 index.raw: regexp.ms
 	$(TROFF) regexp.ms 2> index.raw >/dev/null
diff --git a/doc/unix/Makefile.am b/doc/unix/Makefile.am
index 20a6c42..ec3d70d 100644
--- a/doc/unix/Makefile.am
+++ b/doc/unix/Makefile.am
@@ -18,8 +18,8 @@ unix.html: unix.ms
 	(cat $?; echo ".Tc") | $(UNROFF) document=unix
 
 index.ms: unix.ms index.raw
-	sort -f -t'#' +1 -3 +0n index.raw | awk -f ../util/fixindex.awk\
-	    | awk -f ../util/block.awk >index.ms
+	sort -f -t'#' +1 -3 +0n index.raw | $(AWK) -f ../util/fixindex.awk\
+	    | $(AWK) -f ../util/block.awk >index.ms
 
 index.raw: unix.ms
 	$(TROFF) unix.ms 2> index.raw >/dev/null
diff --git a/doc/xlib/Makefile.am b/doc/xlib/Makefile.am
index 4c4a439..c27c230 100644
--- a/doc/xlib/Makefile.am
+++ b/doc/xlib/Makefile.am
@@ -18,8 +18,8 @@ xlib.html: xlib.ms
 	(cat $?; echo ".Tc") | $(UNROFF) document=xlib
 
 index.ms: xlib.ms index.raw
-	sort -f -t'#' +1 -3 +0n index.raw | awk -f ../util/fixindex.awk\
-	    | awk -f ../util/block.awk >index.ms
+	sort -f -t'#' +1 -3 +0n index.raw | $(AWK) -f ../util/fixindex.awk\
+	    | $(AWK) -f ../util/block.awk >index.ms
 
 index.raw: xlib.ms
 	$(TROFF) xlib.ms 2> index.raw >/dev/null
diff --git a/doc/xt/Makefile.am b/doc/xt/Makefile.am
index a582d3d..2e50784 100644
--- a/doc/xt/Makefile.am
+++ b/doc/xt/Makefile.am
@@ -18,8 +18,8 @@ xt.html: xt.ms
 	(cat $?; echo ".Tc") | $(UNROFF) document=xt
 
 index.ms: xt.ms index.raw
-	sort -f -t'#' +1 -3 +0n index.raw | awk -f ../util/fixindex.awk\
-	    | awk -f ../util/block.awk >index.ms
+	sort -f -t'#' +1 -3 +0n index.raw | $(AWK) -f ../util/fixindex.awk\
+	    | $(AWK) -f ../util/block.awk >index.ms
 
 index.raw: xt.ms
 	$(TROFF) xt.ms 2> index.raw >/dev/null