diff --git a/Makefile.in b/Makefile.in
index 86ede6b2e..648e78f74 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -71,8 +71,8 @@ libdir = @libdir@
 # This is actually the directory where we install our own header files.
 # It is a little different from the generic includedir.
 includedir = @includedir@/iverilog$(suffix)
-mandir = @mandir@
-pdfdir = @docdir@
+man1dir = @mandir@/man1
+docdir = @docdir@
 
 dllib=@DLLIB@
 
@@ -325,26 +325,15 @@ version_tag.h version:
 	    echo '#define VERSION_TAG ""' > version_tag.h; \
 	fi
 
+INSTALL_DOC =
+ifneq ($(MAN),none)
+INSTALL_DOC += installman
+ifneq ($(PS2PDF),none)
 ifeq (@MINGW32@,yes)
-ifeq ($(MAN),none)
-INSTALL_DOC = installman
-INSTALL_PDFDIR = $(prefix)
-else
-ifeq ($(PS2PDF),none)
-INSTALL_DOC = installman
-INSTALL_PDFDIR = $(prefix)
-else
-INSTALL_DOC = installpdf installman
-INSTALL_PDFDIR = $(pdfdir)
-all: dep iverilog-vpi.pdf
+INSTALL_DOC += installpdf
+all: iverilog-vpi.pdf
 endif
 endif
-INSTALL_DOCDIR = $(mandir)/man1
-else
-INSTALL_DOC = installman
-INSTALL_DOCDIR = $(mandir)/man1
-INSTALL_PDFDIR = $(prefix)
-endif
 
 ifeq (@MINGW32@,yes)
 WIN32_INSTALL =
@@ -392,8 +381,8 @@ installdirs: $(srcdir)/mkinstalldirs
 	    "$(DESTDIR)$(includedir)" \
 	    "$(DESTDIR)$(libdir)/ivl$(suffix)" \
 	    "$(DESTDIR)$(libdir)/ivl$(suffix)/include" \
-	    "$(DESTDIR)$(INSTALL_DOCDIR)" \
-	    "$(DESTDIR)$(INSTALL_PDFDIR)"
+	    "$(DESTDIR)$(docdir)" \
+	    "$(DESTDIR)$(man1dir)"
 
 uninstall:
 	$(foreach dir,$(SUBDIRS),$(MAKE) -C $(dir) $@ && ) true
@@ -406,8 +395,8 @@ uninstall:
 	for f in ivl_target.h vpi_user.h _pli_types.h sv_vpi_user.h acc_user.h veriuser.h; \
 	    do rm -f "$(DESTDIR)$(includedir)/$$f"; done
 	-test X$(suffix) = X || rmdir "$(DESTDIR)$(includedir)"
-	rm -f "$(DESTDIR)$(mandir)/man1/iverilog-vpi$(suffix).1" \
-	      "$(DESTDIR)$(pdfdir)/iverilog-vpi$(suffix).pdf"
+	rm -f "$(DESTDIR)$(man1dir)/iverilog-vpi$(suffix).1" \
+	      "$(DESTDIR)$(docdir)/iverilog-vpi$(suffix).pdf"
 
 
 -include $(patsubst %.o, dep/%.d, $O)
diff --git a/driver/Makefile.in b/driver/Makefile.in
index 73f79100f..f0c6831ce 100644
--- a/driver/Makefile.in
+++ b/driver/Makefile.in
@@ -29,8 +29,8 @@ VPATH = $(srcdir)
 bindir = $(exec_prefix)/bin
 libdir = $(exec_prefix)/lib
 includedir = $(prefix)/include
-mandir = @mandir@
-pdfdir = @docdir@
+man1dir = @mandir@/man1
+docdir = @docdir@
 
 dllib=@DLLIB@
 
@@ -111,25 +111,15 @@ iverilog.ps: iverilog.man
 iverilog.pdf: iverilog.ps
 	$(PS2PDF) $< $@
 
+INSTALL_DOC =
+ifneq ($(MAN),none)
+INSTALL_DOC += installman
+ifneq ($(PS2PDF),none)
 ifeq (@MINGW32@,yes)
-ifeq ($(MAN),none)
-INSTALL_DOC = installman
-INSTALL_PDFDIR = $(prefix)
-else
-ifeq ($(PS2PDF),none)
-INSTALL_DOC = installman
-INSTALL_PDFDIR = $(prefix)
-else
-INSTALL_DOC = installpdf installman
-INSTALL_PDFDIR = $(pdfdir)
+INSTALL_DOC += installpdf
 all: iverilog.pdf
 endif
 endif
-INSTALL_DOCDIR = $(mandir)/man1
-else
-INSTALL_DOC = installman
-INSTALL_DOCDIR = $(mandir)/man1
-INSTALL_PDFDIR = $(prefix)
 endif
 
 install: all installdirs installfiles
@@ -138,21 +128,23 @@ F = ./iverilog@EXEEXT@ \
 	$(INSTALL_DOC)
 
 installman: iverilog.man installdirs
-	$(INSTALL_DATA) iverilog.man "$(DESTDIR)$(mandir)/man1/iverilog$(suffix).1"
+	$(INSTALL_DATA) iverilog.man "$(DESTDIR)$(man1dir)/iverilog$(suffix).1"
 
 installpdf: iverilog.pdf installdirs
-	$(INSTALL_DATA) iverilog.pdf "$(DESTDIR)$(pdfdir)/iverilog$(suffix).pdf"
+	$(INSTALL_DATA) iverilog.pdf "$(DESTDIR)$(docdir)/iverilog$(suffix).pdf"
 
 installfiles: $(F) | installdirs
 	$(INSTALL_PROGRAM) ./iverilog@EXEEXT@ "$(DESTDIR)$(bindir)/iverilog$(suffix)@EXEEXT@"
 
 installdirs: $(srcdir)/../mkinstalldirs
-	$(srcdir)/../mkinstalldirs "$(DESTDIR)$(bindir)" \
-		"$(DESTDIR)$(INSTALL_DOCDIR)" \
-		"$(DESTDIR)$(INSTALL_PDFDIR)"
+	$(srcdir)/../mkinstalldirs \
+	    "$(DESTDIR)$(bindir)" \
+	    "$(DESTDIR)$(docdir)" \
+	    "$(DESTDIR)$(man1dir)"
 
 uninstall:
 	rm -f "$(DESTDIR)$(bindir)/iverilog$(suffix)@EXEEXT@"
-	rm -f "$(DESTDIR)$(mandir)/man1/iverilog$(suffix).1" "$(DESTDIR)$(pdfdir)/iverilog$(suffix).pdf"
+	rm -f "$(DESTDIR)$(man1dir)/iverilog$(suffix).1" \
+	      "$(DESTDIR)$(docdir)/iverilog$(suffix).pdf"
 
 -include $(patsubst %.o, dep/%.d, $O)