diff --git a/pkgs/applications/misc/synapse/default.nix b/pkgs/applications/misc/synapse/default.nix
index ebae6fd7cfe..3e7983c667f 100644
--- a/pkgs/applications/misc/synapse/default.nix
+++ b/pkgs/applications/misc/synapse/default.nix
@@ -1,5 +1,5 @@
 { stdenv, fetchurl, gettext, pkgconfig, glib, libnotify, gtk3, libgee
-, keybinder3, json-glib, zeitgeist, vala_0_38, hicolor-icon-theme, gobject-introspection
+, keybinder3, json-glib, zeitgeist, vala, hicolor-icon-theme, gobject-introspection
 }:
 
 let
@@ -13,7 +13,7 @@ in stdenv.mkDerivation rec {
   };
 
   nativeBuildInputs = [
-    pkgconfig gettext vala_0_38
+    pkgconfig gettext vala
     # For setup hook
     gobject-introspection
   ];
diff --git a/pkgs/desktops/gnome-3/default.nix b/pkgs/desktops/gnome-3/default.nix
index 41b0ccf6268..092406b188f 100644
--- a/pkgs/desktops/gnome-3/default.nix
+++ b/pkgs/desktops/gnome-3/default.nix
@@ -54,7 +54,7 @@ lib.makeScope pkgs.newScope (self: with self; {
   libsoup = pkgs.libsoup.override { gnomeSupport = true; };
   libchamplain = pkgs.libchamplain.override { libsoup = libsoup; };
   gnome3 = self // { recurseForDerivations = false; };
-  vala = pkgs.vala_0_42;
+  vala = pkgs.vala_0_44;
   gegl_0_4 = pkgs.gegl_0_4.override { gtk = pkgs.gtk3; };
 
 # ISO installer
diff --git a/pkgs/development/compilers/vala/default.nix b/pkgs/development/compilers/vala/default.nix
index d94437b6a16..dfd40c92ecf 100644
--- a/pkgs/development/compilers/vala/default.nix
+++ b/pkgs/development/compilers/vala/default.nix
@@ -30,12 +30,20 @@ let
         };
 
         # NOTE: the openembedded-core project doesn't have a patch for 0.40.12
-        # or 0.42.4 just yet; we've fixed the single merge conflict in the
-        # patches below and checked them in here.
+        # We've fixed the single merge conflict in the following patch.
         #     0.40.12: https://github.com/openembedded/openembedded-core/raw/8553c52f174af4c8c433c543f806f5ed5c1ec48c/meta/recipes-devtools/vala/vala/disable-graphviz.patch
-        #     0.42.4:  https://github.com/openembedded/openembedded-core/raw/dfbbff39cfd413510abbd60930232a9c6b35d765/meta/recipes-devtools/vala/vala/disable-graphviz.patch
         "0.40" = ./disable-graphviz-0.40.12.patch;
-        "0.42" = ./disable-graphviz-0.42.4.patch;
+
+        "0.42" = fp {
+          commit = "f2b4f9ec6f44dced7f88df849cca68961419eeb8";
+          sha256 = "112qhdzix0d7lfpfcam1cxprzmfzpwypb1226m5ma1vq9qy0sn7g";
+        };
+
+        # NOTE: the openembedded-core project doesn't have a patch for 0.44.1
+        # We've reverted the addition of the "--disable-valadoc" option
+        # and then applied the following patch.
+        #     0.42.4: https://github.com/openembedded/openembedded-core/raw/f2b4f9ec6f44dced7f88df849cca68961419eeb8/meta/recipes-devtools/vala/vala/disable-graphviz.patch
+        "0.44" = ./disable-graphviz-0.44.1.patch;
 
       }.${major} or (throw "no graphviz patch for this version of vala");
 
@@ -88,15 +96,15 @@ let
       homepage = https://wiki.gnome.org/Projects/Vala;
       license = licenses.lgpl21Plus;
       platforms = platforms.unix;
-      maintainers = with maintainers; [ antono jtojnar lethalman peterhoeg ];
+      maintainers = with maintainers; [ antono jtojnar lethalman peterhoeg worldofpeace ];
     };
   });
 
 in rec {
   vala_0_36 = generic {
     major   = "0.36";
-    minor   = "17";
-    sha256  = "1f6qg40zd6jzhbwr3dy4fb66k4qs1xlk2whdyqh64zxxjw0k9pv7";
+    minor   = "18";
+    sha256  = "0csb9skgy663y05kl813dsarzjbfcdsmx5fvz13p8gas3hycciq9";
   };
 
   vala_0_38 = generic {
@@ -108,15 +116,21 @@ in rec {
 
   vala_0_40 = generic {
     major   = "0.40";
-    minor   = "12";
-    sha256  = "1nhk45w5iwg97q3cfybn0i4qz5w9qvk423ndpg6mq6cnna076snx";
+    minor   = "14";
+    sha256  = "0llid9b9cgjcrcclc0pw2skkssb7br7b2clq9cql3p14dl94gki0";
   };
 
   vala_0_42 = generic {
     major   = "0.42";
-    minor   = "4";
-    sha256  = "07jgkx812y7wq4cswwfsf1f4k3lq9hcjra45682bdi8a11nr0a5m";
+    minor   = "6";
+    sha256  = "14024gvs23q323fmd62hqd8jiypaxbjjvamyd782ixbhxmpz8x1p";
   };
 
-  vala = vala_0_42;
+  vala_0_44 = generic {
+    major   = "0.44";
+    minor   = "1";
+    sha256 = "1qiglkgymws6a3m8xz1v8b3na165ywx2dbipp3bdg134bi0w3a4n";
+  };
+
+  vala = vala_0_44;
 }
diff --git a/pkgs/development/compilers/vala/disable-graphviz-0.42.4.patch b/pkgs/development/compilers/vala/disable-graphviz-0.42.4.patch
deleted file mode 100644
index 77e7d6272af..00000000000
--- a/pkgs/development/compilers/vala/disable-graphviz-0.42.4.patch
+++ /dev/null
@@ -1,208 +0,0 @@
-diff --git i/configure.ac w/configure.ac
-index 730c72d7b..af8198637 100644
---- i/configure.ac
-+++ w/configure.ac
-@@ -119,34 +119,38 @@ PKG_CHECK_MODULES(GMODULE, gmodule-2.0 >= $GLIB_REQUIRED)
- AC_SUBST(GMODULE_CFLAGS)
- AC_SUBST(GMODULE_LIBS)
- 
--PKG_CHECK_MODULES(LIBGVC, libgvc >= $LIBGVC_REQUIRED)
--AC_MSG_CHECKING([for CGRAPH])
--cgraph_tmp_LIBADD="$LIBADD"
--cgraph_tmp_CFLAGS="$CFLAGS"
--LIBADD="$LIBADD $LIBGVC_LIBS"
--CFLAGS="$CFLAGS $LIBGVC_CFLAGS"
--AC_RUN_IFELSE(
--	[AC_LANG_SOURCE([
--		#include <gvc.h>
--
--		int main(void) {
--			#ifdef WITH_CGRAPH
--				return 0;
--			#else
--				return -1;
--			#endif
--		}
--	])], [
--		AC_MSG_RESULT([yes])
--		VALAFLAGS="$VALAFLAGS -D WITH_CGRAPH"
--		have_cgraph=yes
--	], [
--		AC_MSG_RESULT([no])
--		have_cgraph=no
--	]
--)
--LIBADD="$cgraph_tmp_LIBADD"
--CFLAGS="$cgraph_tmp_CFLAGS"
-+AC_ARG_ENABLE(graphviz, AS_HELP_STRING([--disable-graphviz], [Disable graphviz usage for valadoc]), enable_graphviz=$enableval, enable_graphviz=yes)
-+if test x$enable_graphviz = xyes; then
-+	PKG_CHECK_MODULES(LIBGVC, libgvc >= $LIBGVC_REQUIRED)
-+	AC_MSG_CHECKING([for CGRAPH])
-+	VALAFLAGS="$VALAFLAGS -D HAVE_GRAPHVIZ"
-+	cgraph_tmp_LIBADD="$LIBADD"
-+	cgraph_tmp_CFLAGS="$CFLAGS"
-+	LIBADD="$LIBADD $LIBGVC_LIBS"
-+	CFLAGS="$CFLAGS $LIBGVC_CFLAGS"
-+	AC_RUN_IFELSE(
-+		[AC_LANG_SOURCE([
-+			#include <gvc.h>
-+			int main(void) {
-+				#ifdef WITH_CGRAPH
-+					return 0;
-+				#else
-+					return -1;
-+				#endif
-+			}
-+		])], [
-+			AC_MSG_RESULT([yes])
-+			VALAFLAGS="$VALAFLAGS -D WITH_CGRAPH"
-+			have_cgraph=yes
-+		], [
-+			AC_MSG_RESULT([no])
-+			have_cgraph=no
-+		]
-+	)
-+	LIBADD="$cgraph_tmp_LIBADD"
-+	CFLAGS="$cgraph_tmp_CFLAGS"
-+fi
-+AM_CONDITIONAL(ENABLE_GRAPHVIZ, test x$enable_graphviz = xyes)
- AM_CONDITIONAL(HAVE_CGRAPH, test "$have_cgraph" = "yes")
- 
- AC_PATH_PROG([XSLTPROC], [xsltproc], :)
-diff --git i/libvaladoc/Makefile.am w/libvaladoc/Makefile.am
-index f3f790e76..3c5dc4c80 100644
---- i/libvaladoc/Makefile.am
-+++ w/libvaladoc/Makefile.am
-@@ -128,10 +128,6 @@ libvaladoc_la_VALASOURCES = \
- 	content/tablerow.vala \
- 	content/taglet.vala \
- 	content/text.vala \
--	charts/chart.vala \
--	charts/chartfactory.vala \
--	charts/hierarchychart.vala \
--	charts/simplechartfactory.vala \
- 	parser/manyrule.vala \
- 	parser/oneofrule.vala \
- 	parser/optionalrule.vala \
-@@ -158,13 +154,24 @@ libvaladoc_la_VALASOURCES = \
- 	highlighter/codetoken.vala \
- 	highlighter/highlighter.vala \
- 	html/basicdoclet.vala \
--	html/htmlchartfactory.vala \
- 	html/linkhelper.vala \
- 	html/cssclassresolver.vala \
- 	html/htmlmarkupwriter.vala \
- 	html/htmlrenderer.vala \
- 	$(NULL)
- 
-+if ENABLE_GRAPHVIZ
-+libvaladoc_la_VALASOURCES += \
-+	charts/chart.vala \
-+	charts/chartfactory.vala \
-+	charts/hierarchychart.vala \
-+	charts/simplechartfactory.vala \
-+	html/htmlchartfactory.vala \
-+	$(NULL)
-+
-+LIBGVC_PKG = --vapidir $(top_srcdir)/vapi --pkg libgvc
-+endif
-+
- libvaladoc@PACKAGE_SUFFIX@_la_SOURCES = \
- 	libvaladoc.vala.stamp \
- 	$(libvaladoc_la_VALASOURCES:.vala=.c) \
-@@ -184,11 +191,11 @@ libvaladoc.vala.stamp: $(libvaladoc_la_VALASOURCES)
- 		--library valadoc \
- 		--vapi valadoc@PACKAGE_SUFFIX@.vapi \
- 		--vapidir $(top_srcdir)/vapi --pkg gmodule-2.0 \
--		--vapidir $(top_srcdir)/vapi --pkg libgvc \
- 		--vapidir $(top_srcdir)/gee --pkg gee \
- 		--vapidir $(top_srcdir)/vala --pkg vala \
- 		--vapidir $(top_srcdir)/ccode --pkg ccode \
- 		--vapidir $(top_srcdir)/codegen --pkg codegen \
-+		$(LIBGVC_PKG) \
- 		--pkg config \
- 		$(filter %.vala %.c,$^)
- 	touch $@
-@@ -217,6 +224,9 @@ nodist_pkgconfig_DATA = valadoc@PACKAGE_SUFFIX@.pc
- 
- valadoc@PACKAGE_SUFFIX@.pc: valadoc.pc
- 	cp $< $@
-+if !ENABLE_GRAPHVIZ
-+	sed -i "s/libgvc //g" $@
-+endif
- 
- vapidir = $(datadir)/vala/vapi
- dist_vapi_DATA = valadoc@PACKAGE_SUFFIX@.vapi
-@@ -224,6 +234,9 @@ nodist_vapi_DATA = valadoc@PACKAGE_SUFFIX@.deps
- 
- valadoc@PACKAGE_SUFFIX@.deps: valadoc.deps
- 	cp $< $@
-+if !ENABLE_GRAPHVIZ
-+	sed -i "s/libgvc//g" $@
-+endif
- 
- EXTRA_DIST = \
- 	$(libvaladoc_la_VALASOURCES) \
-diff --git i/libvaladoc/html/basicdoclet.vala w/libvaladoc/html/basicdoclet.vala
-index 192e488cd..ec0960222 100644
---- i/libvaladoc/html/basicdoclet.vala
-+++ w/libvaladoc/html/basicdoclet.vala
-@@ -46,7 +46,11 @@ public abstract class Valadoc.Html.BasicDoclet : Api.Visitor, Doclet {
- 	protected HtmlRenderer _renderer;
- 	protected Html.MarkupWriter writer;
- 	protected Html.CssClassResolver cssresolver;
-+#if HAVE_GRAPHVIZ
- 	protected Charts.Factory image_factory;
-+#else
-+	protected void* image_factory;
-+#endif
- 	protected ErrorReporter reporter;
- 	protected string package_list_link = "../index.html";
- 
-@@ -120,7 +124,9 @@ public abstract class Valadoc.Html.BasicDoclet : Api.Visitor, Doclet {
- 		this.linker = new LinkHelper ();
- 
- 		_renderer = new HtmlRenderer (settings, this.linker, this.cssresolver);
-+#if HAVE_GRAPHVIZ
- 		this.image_factory = new SimpleChartFactory (settings, linker);
-+#endif
- 	}
- 
- 
-@@ -1026,6 +1032,7 @@ public abstract class Valadoc.Html.BasicDoclet : Api.Visitor, Doclet {
- 	}
- 
- 	protected void write_image_block (Api.Node element) {
-+#if HAVE_GRAPHVIZ
- 		if (element is Class || element is Interface || element is Struct) {
- 			unowned string format = (settings.use_svg_images ? "svg" : "png");
- 			var chart = new Charts.Hierarchy (image_factory, element);
-@@ -1045,6 +1052,7 @@ public abstract class Valadoc.Html.BasicDoclet : Api.Visitor, Doclet {
- 									   this.get_img_path_html (element, format)});
- 			writer.add_usemap (chart);
- 		}
-+#endif
- 	}
- 
- 	public void write_namespace_content (Namespace node, Api.Node? parent) {
-diff --git i/libvaladoc/html/htmlmarkupwriter.vala w/libvaladoc/html/htmlmarkupwriter.vala
-index 5aa4afdea..e79b0b8f5 100644
---- i/libvaladoc/html/htmlmarkupwriter.vala
-+++ w/libvaladoc/html/htmlmarkupwriter.vala
-@@ -51,12 +51,16 @@ public class Valadoc.Html.MarkupWriter : Valadoc.MarkupWriter {
- 		}
- 	}
- 
-+#if HAVE_GRAPHVIZ
- 	public unowned MarkupWriter add_usemap (Charts.Chart chart) {
- 		string? buf = (string?) chart.write_buffer ("cmapx");
- 		if (buf != null) {
- 			raw_text ("\n");
- 			raw_text ((!) buf);
- 		}
-+#else
-+	public unowned MarkupWriter add_usemap (void* chart) {
-+#endif
- 
- 		return this;
- 	}
diff --git a/pkgs/development/compilers/vala/disable-graphviz-0.44.1.patch b/pkgs/development/compilers/vala/disable-graphviz-0.44.1.patch
new file mode 100644
index 00000000000..2752aa1e205
--- /dev/null
+++ b/pkgs/development/compilers/vala/disable-graphviz-0.44.1.patch
@@ -0,0 +1,261 @@
+diff --git a/Makefile.am b/Makefile.am
+index f70234759..b3d6c3833 100644
+--- a/Makefile.am
++++ b/Makefile.am
+@@ -13,19 +13,9 @@ SUBDIRS = \
+ 	doc \
+ 	gobject-introspection \
+ 	vapigen \
+-	$(NULL)
+-
+-if ENABLE_VALADOC
+-SUBDIRS += \
+ 	libvaladoc \
+ 	valadoc \
+ 	$(NULL)
+-endif
+-
+-DISTCHECK_CONFIGURE_FLAGS = \
+-	--enable-valadoc \
+-	--enable-unversioned \
+-	$(NULL)
+ 
+ if ENABLE_UNVERSIONED
+ aclocaldir = $(datadir)/aclocal
+diff --git a/configure.ac b/configure.ac
+index 16ebd1f81..cf23db4b8 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -156,10 +156,11 @@ PKG_CHECK_MODULES(GMODULE, gmodule-2.0 >= $GLIB_REQUIRED)
+ AC_SUBST(GMODULE_CFLAGS)
+ AC_SUBST(GMODULE_LIBS)
+ 
+-AC_ARG_ENABLE(valadoc, AS_HELP_STRING([--disable-valadoc], [Disable valadoc]), enable_valadoc=$enableval, enable_valadoc=yes)
+-if test x$enable_valadoc = xyes; then
++AC_ARG_ENABLE(graphviz, AS_HELP_STRING([--disable-graphviz], [Disable graphviz usage for valadoc]), enable_graphviz=$enableval, enable_graphviz=yes)
++if test x$enable_graphviz = xyes; then
+ 	PKG_CHECK_MODULES(LIBGVC, libgvc >= $LIBGVC_REQUIRED)
+ 	AC_MSG_CHECKING([for CGRAPH])
++	VALAFLAGS="$VALAFLAGS -D HAVE_GRAPHVIZ"
+ 	cgraph_tmp_LIBADD="$LIBADD"
+ 	cgraph_tmp_CFLAGS="$CFLAGS"
+ 	LIBADD="$LIBADD $LIBGVC_LIBS"
+@@ -186,8 +187,8 @@ if test x$enable_valadoc = xyes; then
+ 	LIBADD="$cgraph_tmp_LIBADD"
+ 	CFLAGS="$cgraph_tmp_CFLAGS"
+ fi
++AM_CONDITIONAL(ENABLE_GRAPHVIZ, test x$enable_graphviz = xyes)
+ AM_CONDITIONAL(HAVE_CGRAPH, test "$have_cgraph" = "yes")
+-AM_CONDITIONAL(ENABLE_VALADOC, test x$enable_valadoc = xyes)
+ 
+ AC_PATH_PROG([XSLTPROC], [xsltproc], :)
+ AM_CONDITIONAL(HAVE_XSLTPROC, test "$XSLTPROC" != :)
+diff --git a/doc/Makefile.am b/doc/Makefile.am
+index d2684a0e0..b343c7c10 100644
+--- a/doc/Makefile.am
++++ b/doc/Makefile.am
+@@ -6,16 +6,11 @@ SUBDIRS = \
+ 
+ dist_man_MANS = \
+ 	valac.1 \
++	valadoc.1 \
+ 	vala-gen-introspect.1 \
+ 	vapigen.1 \
+ 	$(NULL)
+ 
+-if ENABLE_VALADOC
+-dist_man_MANS += \
+-	valadoc.1 \
+-	$(NULL)
+-endif
+-
+ EXTRA_DIST = \
+ 	valac.h2m \
+ 	valadoc.h2m \
+@@ -24,11 +19,7 @@ EXTRA_DIST = \
+ 	$(NULL)
+ 
+ if HAVE_HELP2MAN
+-if ENABLE_VALADOC
+ manpages: valac.1 valadoc.1 vala-gen-introspect.1 vapigen.1
+-else
+-manpages: valac.1 vala-gen-introspect.1 vapigen.1
+-endif
+ 	@rm $^
+ 	$(MAKE) $(AM_MAKEFLAGS) $^
+ 
+@@ -37,13 +28,11 @@ valac.1:
+ 		--include $(srcdir)/valac.h2m \
+ 		--libtool --no-info \
+ 		--output=$@
+-if ENABLE_VALADOC
+ valadoc.1:
+ 	$(HELP2MAN) $(top_builddir)/valadoc/valadoc \
+ 		--include $(srcdir)/valadoc.h2m \
+ 		--libtool --no-info \
+ 		--output=$@
+-endif
+ vala-gen-introspect.1:
+ 	$(HELP2MAN) $(top_builddir)/gobject-introspection/gen-introspect \
+ 		--include $(srcdir)/vala-gen-introspect.h2m \
+@@ -60,15 +49,12 @@ endif
+ if ENABLE_UNVERSIONED
+ install-data-hook:
+ 	cd $(DESTDIR)$(man1dir) && $(LN_S) -f valac@PACKAGE_SUFFIX@.1 valac.1
+-if ENABLE_VALADOC
+ 	cd $(DESTDIR)$(man1dir) && $(LN_S) -f valadoc@PACKAGE_SUFFIX@.1 valadoc.1
+-endif
+ 	cd $(DESTDIR)$(man1dir) && $(LN_S) -f vala-gen-introspect@PACKAGE_SUFFIX@.1 vala-gen-introspect.1
+ 	cd $(DESTDIR)$(man1dir) && $(LN_S) -f vapigen@PACKAGE_SUFFIX@.1 vapigen.1
+ endif
+ 
+ 
+-if ENABLE_VALADOC
+ COMMON_VALADOCFLAGS = \
+ 	--force \
+ 	--verbose \
+@@ -150,7 +136,6 @@ internal-apis/valadoc: $(valadoc_VALASOURCES) internal-apis/codegen
+ 	@touch $@
+ 
+ internal-api-docs: internal-apis/gee internal-apis/vala internal-apis/ccode internal-apis/codegen internal-apis/valadoc
+-endif
+ 
+ clean-local:
+ 	rm -rf $(builddir)/internal-apis
+diff --git a/libvaladoc/Makefile.am b/libvaladoc/Makefile.am
+index 7456fb836..107338e91 100644
+--- a/libvaladoc/Makefile.am
++++ b/libvaladoc/Makefile.am
+@@ -119,10 +119,6 @@ libvaladoc_la_VALASOURCES = \
+ 	content/tablerow.vala \
+ 	content/taglet.vala \
+ 	content/text.vala \
+-	charts/chart.vala \
+-	charts/chartfactory.vala \
+-	charts/hierarchychart.vala \
+-	charts/simplechartfactory.vala \
+ 	parser/manyrule.vala \
+ 	parser/oneofrule.vala \
+ 	parser/optionalrule.vala \
+@@ -149,13 +145,24 @@ libvaladoc_la_VALASOURCES = \
+ 	highlighter/codetoken.vala \
+ 	highlighter/highlighter.vala \
+ 	html/basicdoclet.vala \
+-	html/htmlchartfactory.vala \
+ 	html/linkhelper.vala \
+ 	html/cssclassresolver.vala \
+ 	html/htmlmarkupwriter.vala \
+ 	html/htmlrenderer.vala \
+ 	$(NULL)
+ 
++if ENABLE_GRAPHVIZ
++libvaladoc_la_VALASOURCES += \
++	charts/chart.vala \
++	charts/chartfactory.vala \
++	charts/hierarchychart.vala \
++	charts/simplechartfactory.vala \
++	html/htmlchartfactory.vala \
++	$(NULL)
++
++LIBGVC_PKG = --vapidir $(top_srcdir)/vapi --pkg libgvc
++endif
++
+ libvaladoc@PACKAGE_SUFFIX@_la_SOURCES = \
+ 	libvaladoc.vala.stamp \
+ 	$(libvaladoc_la_VALASOURCES:.vala=.c) \
+@@ -175,11 +182,11 @@ libvaladoc.vala.stamp: $(libvaladoc_la_VALASOURCES)
+ 		--library valadoc \
+ 		--vapi valadoc@PACKAGE_SUFFIX@.vapi \
+ 		--vapidir $(top_srcdir)/vapi --pkg gmodule-2.0 \
+-		--vapidir $(top_srcdir)/vapi --pkg libgvc \
+ 		--vapidir $(top_srcdir)/gee --pkg gee \
+ 		--vapidir $(top_srcdir)/vala --pkg vala \
+ 		--vapidir $(top_srcdir)/ccode --pkg ccode \
+ 		--vapidir $(top_srcdir)/codegen --pkg codegen \
++		$(LIBGVC_PKG) \
+ 		--pkg config \
+ 		$(filter %.vala %.c,$^)
+ 	touch $@
+@@ -207,6 +214,9 @@ nodist_pkgconfig_DATA = valadoc@PACKAGE_SUFFIX@.pc
+ 
+ valadoc@PACKAGE_SUFFIX@.pc: valadoc.pc
+ 	cp $< $@
++if !ENABLE_GRAPHVIZ
++	sed -i "s/libgvc //g" $@
++endif
+ 
+ vapidir = $(datadir)/vala/vapi
+ dist_vapi_DATA = valadoc@PACKAGE_SUFFIX@.vapi
+@@ -214,6 +224,9 @@ nodist_vapi_DATA = valadoc@PACKAGE_SUFFIX@.deps
+ 
+ valadoc@PACKAGE_SUFFIX@.deps: valadoc.deps
+ 	cp $< $@
++if !ENABLE_GRAPHVIZ
++	sed -i "s/libgvc//g" $@
++endif
+ 
+ EXTRA_DIST = \
+ 	$(libvaladoc_la_VALASOURCES) \
+diff --git a/libvaladoc/html/basicdoclet.vala b/libvaladoc/html/basicdoclet.vala
+index 46578c28f..f6ce7097c 100644
+--- a/libvaladoc/html/basicdoclet.vala
++++ b/libvaladoc/html/basicdoclet.vala
+@@ -46,7 +46,11 @@ public abstract class Valadoc.Html.BasicDoclet : Api.Visitor, Doclet {
+ 	protected HtmlRenderer _renderer;
+ 	protected Html.MarkupWriter writer;
+ 	protected Html.CssClassResolver cssresolver;
++#if HAVE_GRAPHVIZ
+ 	protected Charts.Factory image_factory;
++#else
++	protected void* image_factory;
++#endif
+ 	protected ErrorReporter reporter;
+ 	protected string package_list_link = "../index.html";
+ 
+@@ -120,7 +124,9 @@ public abstract class Valadoc.Html.BasicDoclet : Api.Visitor, Doclet {
+ 		this.linker = new LinkHelper ();
+ 
+ 		_renderer = new HtmlRenderer (settings, this.linker, this.cssresolver);
++#if HAVE_GRAPHVIZ
+ 		this.image_factory = new SimpleChartFactory (settings, linker);
++#endif
+ 	}
+ 
+ 
+@@ -1025,6 +1031,7 @@ public abstract class Valadoc.Html.BasicDoclet : Api.Visitor, Doclet {
+ 	}
+ 
+ 	protected void write_image_block (Api.Node element) {
++#if HAVE_GRAPHVIZ
+ 		if (element is Class || element is Interface || element is Struct) {
+ 			unowned string format = (settings.use_svg_images ? "svg" : "png");
+ 			var chart = new Charts.Hierarchy (image_factory, element);
+@@ -1044,6 +1051,7 @@ public abstract class Valadoc.Html.BasicDoclet : Api.Visitor, Doclet {
+ 									   this.get_img_path_html (element, format)});
+ 			writer.add_usemap (chart);
+ 		}
++#endif
+ 	}
+ 
+ 	public void write_namespace_content (Namespace node, Api.Node? parent) {
+diff --git a/libvaladoc/html/htmlmarkupwriter.vala b/libvaladoc/html/htmlmarkupwriter.vala
+index 5aa4afdea..e79b0b8f5 100644
+--- a/libvaladoc/html/htmlmarkupwriter.vala
++++ b/libvaladoc/html/htmlmarkupwriter.vala
+@@ -51,12 +51,16 @@ public class Valadoc.Html.MarkupWriter : Valadoc.MarkupWriter {
+ 		}
+ 	}
+ 
++#if HAVE_GRAPHVIZ
+ 	public unowned MarkupWriter add_usemap (Charts.Chart chart) {
+ 		string? buf = (string?) chart.write_buffer ("cmapx");
+ 		if (buf != null) {
+ 			raw_text ("\n");
+ 			raw_text ((!) buf);
+ 		}
++#else
++	public unowned MarkupWriter add_usemap (void* chart) {
++#endif
+ 
+ 		return this;
+ 	}
diff --git a/pkgs/development/libraries/libdbusmenu/default.nix b/pkgs/development/libraries/libdbusmenu/default.nix
index 8fbbae43f61..e064084f695 100644
--- a/pkgs/development/libraries/libdbusmenu/default.nix
+++ b/pkgs/development/libraries/libdbusmenu/default.nix
@@ -1,7 +1,7 @@
 { stdenv, fetchurl, lib, file
 , pkgconfig, intltool
 , glib, dbus-glib, json-glib
-, gobject-introspection, vala_0_38, gnome-doc-utils
+, gobject-introspection, vala, gnome-doc-utils
 , gtkVersion ? null, gtk2 ? null, gtk3 ? null }:
 
 with lib;
@@ -18,11 +18,11 @@ stdenv.mkDerivation rec {
     sha256 = "12l7z8dhl917iy9h02sxmpclnhkdjryn08r8i4sr8l3lrlm4mk5r";
   };
 
-  nativeBuildInputs = [ pkgconfig intltool ];
+  nativeBuildInputs = [ vala pkgconfig intltool ];
 
   buildInputs = [
     glib dbus-glib json-glib
-    gobject-introspection vala_0_38 gnome-doc-utils
+    gobject-introspection gnome-doc-utils
   ] ++ optional (gtkVersion != null) (if gtkVersion == "2" then gtk2 else gtk3);
 
   postPatch = ''
@@ -49,9 +49,9 @@ stdenv.mkDerivation rec {
   doCheck = false; # generates shebangs in check phase, too lazy to fix
 
   installFlags = [
-    "sysconfdir=\${out}/etc"
+    "sysconfdir=${placeholder ''out''}/etc"
     "localstatedir=\${TMPDIR}"
-    "typelibdir=\${out}/lib/girepository-1.0"
+    "typelibdir=${placeholder ''out''}/lib/girepository-1.0"
   ];
 
   meta = {
diff --git a/pkgs/development/libraries/libhttpseverywhere/default.nix b/pkgs/development/libraries/libhttpseverywhere/default.nix
index c1ec533ba5b..cf5c80c9b21 100644
--- a/pkgs/development/libraries/libhttpseverywhere/default.nix
+++ b/pkgs/development/libraries/libhttpseverywhere/default.nix
@@ -1,5 +1,5 @@
-{ stdenv, fetchurl, pkgconfig, meson, ninja, makeFontsConf, vala_0_40
-, gnome3, glib, json-glib, libarchive, libsoup, gobject-introspection }:
+{ stdenv, fetchurl, pkgconfig, meson, ninja, makeFontsConf, vala, fetchpatch
+, gnome3, glib, json-glib, libarchive, libsoup, gobject-introspection, valadoc }:
 
 let
   pname = "libhttpseverywhere";
@@ -12,10 +12,17 @@ in stdenv.mkDerivation rec {
     sha256 = "1jmn6i4vsm89q1axlq4ajqkzqmlmjaml9xhw3h9jnal46db6y00w";
   };
 
-  # Broken with newest Vala https://gitlab.gnome.org/GNOME/libhttpseverywhere/issues/1
-  nativeBuildInputs = [ vala_0_40 gobject-introspection meson ninja pkgconfig ];
+  nativeBuildInputs = [ vala gobject-introspection meson ninja pkgconfig ];
   buildInputs = [ glib gnome3.libgee json-glib libsoup libarchive ];
 
+  # Fixes build with vala >=0.42
+  patches = [
+    (fetchpatch {
+      url = "https://gitlab.gnome.org/GNOME/libhttpseverywhere/commit/6da08ef1ade9ea267cecf14dd5cb2c3e6e5e50cb.patch";
+      sha256 = "1nwjlh8iqgjayccwdh0fbpq2g1h8bg1k1g9i324f2bhhvyhmpq8f";
+    })
+  ];
+
   mesonFlags = [ "-Denable_valadoc=true" ];
 
   doCheck = true;
diff --git a/pkgs/tools/package-management/packagekit/default.nix b/pkgs/tools/package-management/packagekit/default.nix
index 5b787220040..90893c8b7d9 100644
--- a/pkgs/tools/package-management/packagekit/default.nix
+++ b/pkgs/tools/package-management/packagekit/default.nix
@@ -1,6 +1,6 @@
 { stdenv, fetchFromGitHub, lib
 , intltool, glib, pkgconfig, polkit, python, sqlite
-, gobject-introspection, vala_0_38, gtk-doc, autoreconfHook, autoconf-archive
+, gobject-introspection, vala, gtk-doc, autoreconfHook, autoconf-archive
 # TODO: set enableNixBackend to true, as soon as it builds
 , nix, enableNixBackend ? false, boost
 , enableCommandNotFound ? false
@@ -20,7 +20,7 @@ stdenv.mkDerivation rec {
     sha256 = "02wq3jw3mkdld90irh5vdfd5bri2g1p89mhrmj56kvif1fqak46x";
   };
 
-  buildInputs = [ glib polkit python gobject-introspection vala_0_38 ]
+  buildInputs = [ glib polkit python gobject-introspection vala ]
                   ++ lib.optional enableSystemd systemd
                   ++ lib.optional enableBashCompletion bash-completion;
   propagatedBuildInputs = [ sqlite nix boost ];
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 407cb376533..b735c25f91e 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -7688,6 +7688,7 @@ in
     vala_0_38
     vala_0_40
     vala_0_42
+    vala_0_44
     vala;
 
   valadoc = callPackage ../development/tools/valadoc { };