diff --git a/development/sdcc/patches/source-tree.patch b/development/sdcc/patches/source-tree.patch
index cb5d8d813b..93c2798f75 100644
--- a/development/sdcc/patches/source-tree.patch
+++ b/development/sdcc/patches/source-tree.patch
@@ -1,10 +1,10 @@
 diff --git a/device/lib/Makefile.in b/device/lib/Makefile.in
 --- a/device/lib/Makefile.in
 +++ b/device/lib/Makefile.in
-@@ -583,19 +583,11 @@
- 	$(CP_U) -r $(MODELS) mcs51 ds390 ds400 z80 z180 ez80_z80 r2k r3ka tlcs90 gbz80 hc08 s08 stm8 pdk14 pdk15 $(sdcc_libdir)/src
+@@ -599,19 +599,11 @@
+ 	$(CP_U) -r $(MODELS) mcs51 ds390 ds400 z80 z180 ez80_z80 r2k r3ka tlcs90 gbz80 hc08 s08 stm8 pdk13 pdk14 pdk15 $(sdcc_libdir)/src
  
- 	for src in $(MODELS) ds390 ds400 z80 z180 ez80_z80 r2k r3ka tlcs90 gbz80 hc08 s08 stm8 pdk14 pdk15 pic14 pic16; do \
+ 	for src in $(MODELS) ds390 ds400 z80 z180 ez80_z80 r2k r3ka tlcs90 gbz80 hc08 s08 stm8 pdk13 pdk14 pdk15 pic14 pic16; do \
 -	  find $(sdcc_libdir)/src/$$src -depth \
 -	    \( -name '*.rel' -o -name '*.dump*' -o -name '*.sym' -o -name '*.o' -o -name '*.lib' -o \
 -	    -name '*.lst' -o -name '*.asm' -o -name '.svn' -o -name 'autom4te.cache' -o \
diff --git a/development/sdcc/sdcc.SlackBuild b/development/sdcc/sdcc.SlackBuild
index 9a9fdf5f1f..8e6a39a06f 100644
--- a/development/sdcc/sdcc.SlackBuild
+++ b/development/sdcc/sdcc.SlackBuild
@@ -2,7 +2,7 @@
 
 # Slackware build script for sdcc
 
-# Copyright 2014-2019 Kyle Guinn <elyk03@gmail.com>
+# Copyright 2014-2020 Kyle Guinn <elyk03@gmail.com>
 # All rights reserved.
 #
 # Redistribution and use of this script, with or without modification, is
@@ -23,7 +23,7 @@
 #  ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 PRGNAM=sdcc
-VERSION=${VERSION:-3.9.0}
+VERSION=${VERSION:-4.0.0}
 BUILD=${BUILD:-1}
 TAG=${TAG:-_SBo}
 
@@ -81,6 +81,10 @@ patch -p1 < $CWD/patches/source-tree.patch
 # Avoid creating empty man directories.
 sed -i '/(man1dir)/d' sim/ucsim/doc/Makefile.in
 
+# make considers device/lib/pic14/aclocal.m4 out-of-date and tries to
+# rebuild it using aclocal-1.16 which doesn't exist yet on Slackware 14.2.
+(cd device/lib/pic14 && autoreconf -vif)
+
 # Requires lyx, latex2html, possibly others.  Untested.
 if [ "${ENABLE_DOC:-no}" != 'no' ]; then
   enable_doc='--enable-doc'
diff --git a/development/sdcc/sdcc.info b/development/sdcc/sdcc.info
index 7d3d06ddd5..82b700329c 100644
--- a/development/sdcc/sdcc.info
+++ b/development/sdcc/sdcc.info
@@ -1,8 +1,8 @@
 PRGNAM="sdcc"
-VERSION="3.9.0"
+VERSION="4.0.0"
 HOMEPAGE="http://sdcc.sourceforge.net/"
-DOWNLOAD="https://sourceforge.net/projects/sdcc/files/sdcc/3.9.0/sdcc-src-3.9.0.tar.bz2"
-MD5SUM="e50fc62cd9cdfa977af536dfd2d99351"
+DOWNLOAD="https://sourceforge.net/projects/sdcc/files/sdcc/4.0.0/sdcc-src-4.0.0.tar.bz2"
+MD5SUM="eac8f83af265dca1f3e4c79abcd43c6c"
 DOWNLOAD_x86_64=""
 MD5SUM_x86_64=""
 REQUIRES=""