diff --git a/pkgs/development/libraries/libmilter/darwin.patch b/pkgs/development/libraries/libmilter/darwin.patch
new file mode 100644
index 000000000000..be46662d6b38
--- /dev/null
+++ b/pkgs/development/libraries/libmilter/darwin.patch
@@ -0,0 +1,28 @@
+Fix build issues on Darwin.
+
+--- a/devtools/OS/Darwin	2014-03-05 01:59:45.000000000 +0100
++++ b/devtools/OS/Darwin	2020-05-18 14:47:57.000000000 +0200
+@@ -8,6 +8,8 @@
+ #    We look a lot more like 4.4BSD than NeXTStep or OpenStep.
+ #
+ define(`confCC', `cc -traditional-cpp -pipe ${Extra_CC_Flags}')
++define(`confCCOPTS_SO', `-fPIC')
++define(`confSOEXT', `dylib')
+ define(`confMAPDEF', `-DNEWDB -DNIS -DMAP_REGEX -DNETINFO -DAUTO_NETINFO_ALIASES -DAUTO_NETINFO_HOSTS')
+ define(`confENVDEF', `-DDARWIN')
+ define(`confLDOPTS', `${Extra_LD_Flags}')
+--- a/sendmail/sendmail.h	2020-05-18 14:51:17.000000000 +0200
++++ b/sendmail/sendmail.h	2020-05-18 14:51:00.000000000 +0200
+@@ -104,7 +104,11 @@
+ # endif /* NETX25 */
+ 
+ # if NAMED_BIND
+-#  include <arpa/nameser.h>
++#  ifdef __APPLE__
++#   include <arpa/nameser_compat.h>
++#  else
++#   include <arpa/nameser.h>
++#  endif
+ #  ifdef NOERROR
+ #   undef NOERROR		/* avoid <sys/streams.h> conflict */
+ #  endif /* NOERROR */
diff --git a/pkgs/development/libraries/libmilter/default.nix b/pkgs/development/libraries/libmilter/default.nix
index 8d677d858de8..f937d818a559 100644
--- a/pkgs/development/libraries/libmilter/default.nix
+++ b/pkgs/development/libraries/libmilter/default.nix
@@ -28,10 +28,11 @@ stdenv.mkDerivation rec {
       define(\`confLIBGRP', \`root')
       APPENDDEF(\`confENVDEF', \`-DNETINET6')
     EOF
+    export MILTER_SOVER=1
     sh Build -f ./a.m4
   '';
 
-  patches = [ ./install.patch ./sharedlib.patch ./glibc-2.30.patch ];
+  patches = [ ./install.patch ./sharedlib.patch ./glibc-2.30.patch ./darwin.patch ];
 
   nativeBuildInputs = [ m4 ];
 
diff --git a/pkgs/development/libraries/libmilter/sharedlib.patch b/pkgs/development/libraries/libmilter/sharedlib.patch
index bbc69a516ffd..1e256c59ec3e 100644
--- a/pkgs/development/libraries/libmilter/sharedlib.patch
+++ b/pkgs/development/libraries/libmilter/sharedlib.patch
@@ -16,28 +16,29 @@ diff -Nru sendmail-8.14.3.orig/devtools/M4/UNIX/milterlibrary.m4 sendmail-8.14.3
 +#
 +divert(0)dnl
 +include(confBUILDTOOLSDIR`/M4/'bldM4_TYPE_DIR`/links.m4')dnl
++define(`confSOEXT', ifdef(`confSOEXT', `confSOEXT', `so'))dnl
 +bldLIST_PUSH_ITEM(`bldC_PRODUCTS', bldCURRENT_PRODUCT)dnl
-+bldPUSH_TARGET(bldCURRENT_PRODUCT`.so' bldCURRENT_PRODUCT`.a')dnl
++bldPUSH_TARGET(bldCURRENT_PRODUCT`.'confSOEXT bldCURRENT_PRODUCT`.a')dnl
 +bldPUSH_INSTALL_TARGET(`install-'bldCURRENT_PRODUCT)dnl
 +bldPUSH_CLEAN_TARGET(bldCURRENT_PRODUCT`-clean')dnl
 +
 +include(confBUILDTOOLSDIR`/M4/'bldM4_TYPE_DIR`/defines.m4')
 +divert(bldTARGETS_SECTION)
-+bldCURRENT_PRODUCT.so: ${BEFORE} ${bldCURRENT_PRODUCT`OBJS'}
-+	${CCLINK} ${LDOPTS_SO} -o bldCURRENT_PRODUCT.so -Wl,confSONAME,bldCURRENT_PRODUCT.so.${MILTER_SOVER} ${bldCURRENT_PRODUCT`OBJS'} -lc ${LIBS}
++bldCURRENT_PRODUCT`.'confSOEXT: ${BEFORE} ${bldCURRENT_PRODUCT`OBJS'}
++	${CCLINK} ${LDOPTS_SO} -o bldCURRENT_PRODUCT.confSOEXT ifdef(`confSONAME',`-Wl,confSONAME,bldCURRENT_PRODUCT.confSOEXT.${MILTER_SOVER}') ${bldCURRENT_PRODUCT`OBJS'} -lc ${LIBS}
 +bldCURRENT_PRODUCT.a: ${BEFORE} ${bldCURRENT_PRODUCT`OBJS'}
 +	${AR} ${AROPTS} bldCURRENT_PRODUCT.a ${bldCURRENT_PRODUCT`OBJS'}
 +	${RANLIB} ${RANLIBOPTS} bldCURRENT_PRODUCT.a
 +ifdef(`bldLINK_SOURCES', `bldMAKE_SOURCE_LINKS(bldLINK_SOURCES)')
 +
-+install-`'bldCURRENT_PRODUCT: bldCURRENT_PRODUCT.so bldCURRENT_PRODUCT.a
++install-`'bldCURRENT_PRODUCT: bldCURRENT_PRODUCT.confSOEXT bldCURRENT_PRODUCT.a
 +ifdef(`bldINSTALLABLE', `	ifdef(`confMKDIR', `if [ ! -d "${DESTDIR}${bldINSTALL_DIR`'LIBDIR}" ]; then confMKDIR -p "${DESTDIR}${bldINSTALL_DIR`'LIBDIR}"; else :; fi ')
-+	${INSTALL} -c bldCURRENT_PRODUCT.so "${DESTDIR}${LIBDIR}/bldCURRENT_PRODUCT.so.${MILTER_SOVER}"
-+	${LN} ${LNOPTS} bldCURRENT_PRODUCT.so.${MILTER_SOVER} "${DESTDIR}${LIBDIR}/bldCURRENT_PRODUCT.so"
-+	${INSTALL} -c bldCURRENT_PRODUCT.a "${DESTDIR}${LIBDIR}"')
++	${INSTALL} -c bldCURRENT_PRODUCT.confSOEXT "${DESTDIR}${LIBDIR}/bldCURRENT_PRODUCT.confSOEXT.${MILTER_SOVER}"
++	${LN} ${LNOPTS} bldCURRENT_PRODUCT.confSOEXT.${MILTER_SOVER} "${DESTDIR}${LIBDIR}/bldCURRENT_PRODUCT.confSOEXT"
++	${INSTALL} -c -m 644 bldCURRENT_PRODUCT.a "${DESTDIR}${LIBDIR}"')
 +
 +bldCURRENT_PRODUCT-clean:
-+	rm -f ${OBJS} bldCURRENT_PRODUCT.so bldCURRENT_PRODUCT.a ${MANPAGES}
++	rm -f ${OBJS} bldCURRENT_PRODUCT.confSOEXT bldCURRENT_PRODUCT.a ${MANPAGES}
 +
 +divert(0)
 +COPTS+= confCCOPTS_SO