diff --git a/Makefile b/Makefile
index 91d69a1..97319fc 100644
--- a/Makefile
+++ b/Makefile
@@ -16,7 +16,10 @@
 DESTDIR ?= dist
 PREFIX ?= /usr/local
 
-MANDIR != [ $(PREFIX) = / ] && printf '/usr/share/man\n' \
+# normalized prefix
+PREFIX_N != (test -d $(PREFIX) && [ '-' != $(PREFIX) ] \
+	&& CDPATH= cd -P -- $(PREFIX) && pwd -P)
+MANDIR != [ $(PREFIX_N) = / ] && printf '/usr/share/man\n' \
 	|| printf '/share/man\n'
 SYSEXITS != printf '\043include <sysexits.h>\n' | cpp -M - | sed 's/ /\n/g' \
 	| sed -n 's/sysexits\.h//p' || printf 'include\n'
@@ -29,7 +32,7 @@ RUSTLIBS = --extern getopt=build/o/libgetopt.rlib \
 CFLAGS += -I$(SYSEXITS)
 
 .PHONY: all
-all: docs dj false fop hru intcmp mm npc rpn scrut str strcmp swab true
+all: dj false fop hru intcmp mm npc rpn scrut str strcmp swab true
 
 # keep build/include until bindgen(1) has stdin support
 # https://github.com/rust-lang/rust-bindgen/issues/2703
@@ -40,7 +43,7 @@ build:
 clean:
 	rm -rf build dist
 
-dist: all
+dist: all docs
 	mkdir -p $(DESTDIR)/$(PREFIX)/bin $(DESTDIR)/$(PREFIX)/share/man/man1
 	cp build/bin/* $(DESTDIR)/$(PREFIX)/bin
 	cp build/docs/*.1 $(DESTDIR)/$(PREFIX)/$(MANDIR)/man1