diff --git a/source/dub/compilers/compiler.d b/source/dub/compilers/compiler.d
index 7f39bcf..2eb8a9a 100644
--- a/source/dub/compilers/compiler.d
+++ b/source/dub/compilers/compiler.d
@@ -72,7 +72,7 @@
 
 	/// Replaces high level fields with low level fields and converts
 	/// dmd flags to compiler-specific flags
-	void prepareBuildSettings(ref BuildSettings settings, in ref BuildPlatform platform, BuildSetting supported_fields = BuildSetting.all) const;
+	void prepareBuildSettings(ref BuildSettings settings, const scope ref BuildPlatform platform, BuildSetting supported_fields = BuildSetting.all) const;
 
 	/// Removes any dflags that match one of the BuildOptions values and populates the BuildSettings.options field.
 	void extractBuildOptions(ref BuildSettings settings) const;
diff --git a/source/dub/compilers/dmd.d b/source/dub/compilers/dmd.d
index 9936713..6f55ee0 100644
--- a/source/dub/compilers/dmd.d
+++ b/source/dub/compilers/dmd.d
@@ -167,7 +167,7 @@
 		if (!isWow64.isNull && !isWow64.get) assert(!bp.architecture.canFind("x86_omf"));
 		if (!isWow64.isNull &&  isWow64.get) assert(bp.architecture.canFind("x86_64"));
 	}
-	
+
 	version (LDC) unittest {
 		BuildSettings settings;
 		auto compiler = new DMDCompiler;
@@ -180,7 +180,8 @@
 		assert(!bp.architecture.canFind("x86_omf"));
 	}
 
-	void prepareBuildSettings(ref BuildSettings settings, in ref BuildPlatform platform, BuildSetting fields = BuildSetting.all) const
+	void prepareBuildSettings(ref BuildSettings settings, const scope ref BuildPlatform platform,
+                              BuildSetting fields = BuildSetting.all) const
 	{
 		enforceBuildRequirements(settings);
 
diff --git a/source/dub/compilers/gdc.d b/source/dub/compilers/gdc.d
index bb0c27b..cec2dbc 100644
--- a/source/dub/compilers/gdc.d
+++ b/source/dub/compilers/gdc.d
@@ -85,7 +85,7 @@
 		);
 	}
 
-	void prepareBuildSettings(ref BuildSettings settings, in ref BuildPlatform platform, BuildSetting fields = BuildSetting.all) const
+	void prepareBuildSettings(ref BuildSettings settings, const scope ref BuildPlatform platform, BuildSetting fields = BuildSetting.all) const
 	{
 		enforceBuildRequirements(settings);
 
diff --git a/source/dub/compilers/ldc.d b/source/dub/compilers/ldc.d
index f62e964..8273e97 100644
--- a/source/dub/compilers/ldc.d
+++ b/source/dub/compilers/ldc.d
@@ -101,7 +101,7 @@
 		);
 	}
 
-	void prepareBuildSettings(ref BuildSettings settings, in ref BuildPlatform platform, BuildSetting fields = BuildSetting.all) const
+	void prepareBuildSettings(ref BuildSettings settings, const scope ref BuildPlatform platform, BuildSetting fields = BuildSetting.all) const
 	{
 		enforceBuildRequirements(settings);
 
diff --git a/source/dub/compilers/utils.d b/source/dub/compilers/utils.d
index 12c55f3..171f487 100644
--- a/source/dub/compilers/utils.d
+++ b/source/dub/compilers/utils.d
@@ -40,7 +40,7 @@
 	Linker files include static/dynamic libraries, resource files, object files
 	and DLL definition files.
 */
-bool isLinkerFile(in ref BuildPlatform platform, string f)
+bool isLinkerFile(const scope ref BuildPlatform platform, string f)
 {
 	import std.path;
 	switch (extension(f)) {
@@ -79,7 +79,7 @@
 	This function tries to invoke "pkg-config" if possible and falls back to
 	direct flag translation if that fails.
 */
-void resolveLibs(ref BuildSettings settings, in ref BuildPlatform platform)
+void resolveLibs(ref BuildSettings settings, const scope ref BuildPlatform platform)
 {
 	import std.string : format;
 	import std.array : array;
diff --git a/source/dub/dependencyresolver.d b/source/dub/dependencyresolver.d
index 85e97de..eb4462c 100644
--- a/source/dub/dependencyresolver.d
+++ b/source/dub/dependencyresolver.d
@@ -45,8 +45,8 @@
 			ret ^= typeid(CONFIGS).getHash(&configs);
 			return ret;
 		}
-		bool opEqual(in ref TreeNodes other) const { return pack == other.pack && configs == other.configs; }
-		int opCmp(in ref TreeNodes other) const {
+		bool opEqual(const scope ref TreeNodes other) const { return pack == other.pack && configs == other.configs; }
+		int opCmp(const scope ref TreeNodes other) const {
 			if (pack != other.pack) return pack < other.pack ? -1 : 1;
 			if (configs != other.configs) return configs < other.configs ? -1 : 1;
 			return 0;
@@ -66,8 +66,8 @@
 			ret ^= typeid(CONFIG).getHash(&config);
 			return ret;
 		}
-		bool opEqual(in ref TreeNode other) const { return pack == other.pack && config == other.config; }
-		int opCmp(in ref TreeNode other) const {
+		bool opEqual(const scope ref TreeNode other) const { return pack == other.pack && config == other.config; }
+		int opCmp(const scope ref TreeNode other) const {
 			if (pack != other.pack) return pack < other.pack ? -1 : 1;
 			if (config != other.config) return config < other.config ? -1 : 1;
 			return 0;
@@ -286,7 +286,7 @@
 
 		string failedNode;
 
-		this(TreeNode parent, TreeNodes dep, in ref ResolveContext context, string file = __FILE__, size_t line = __LINE__)
+		this(TreeNode parent, TreeNodes dep, const scope ref ResolveContext context, string file = __FILE__, size_t line = __LINE__)
 		{
 			auto m = format("Unresolvable dependencies to package %s:", dep.pack.basePackageName);
 			super(m, file, line);
diff --git a/source/dub/generators/build.d b/source/dub/generators/build.d
index 5f54d4a..75250f4 100644
--- a/source/dub/generators/build.d
+++ b/source/dub/generators/build.d
@@ -27,7 +27,7 @@
 import std.string;
 import std.encoding : sanitize;
 
-string getObjSuffix(in ref BuildPlatform platform)
+string getObjSuffix(const scope ref BuildPlatform platform)
 {
     return platform.platform.canFind("windows") ? ".obj" : ".o";
 }
@@ -412,7 +412,7 @@
 	/// Calls with path that resolve to the same file on the filesystem will return the same,
 	/// unless they include different symbolic links (which are not resolved).
 
-	static string pathToObjName(in ref BuildPlatform platform, string path)
+	static string pathToObjName(const scope ref BuildPlatform platform, string path)
 	{
 		import std.digest.crc : crc32Of;
 		import std.path : buildNormalizedPath, dirSeparator, relativePath, stripDrive;
@@ -593,7 +593,7 @@
 	return prj.path ~ "source/app.d";
 }
 
-private NativePath getTargetPath(in ref BuildSettings bs, in ref GeneratorSettings settings)
+private NativePath getTargetPath(const scope ref BuildSettings bs, const scope ref GeneratorSettings settings)
 {
 	return NativePath(bs.targetPath) ~ settings.compiler.getTargetFileName(bs, settings.platform);
 }
diff --git a/source/dub/generators/generator.d b/source/dub/generators/generator.d
index 97d2985..3c5d6d7 100644
--- a/source/dub/generators/generator.d
+++ b/source/dub/generators/generator.d
@@ -308,7 +308,7 @@
 		visited.clear();
 
 		// 1. downwards inherits versions, debugVersions, and inheritable build settings
-		static void configureDependencies(in ref TargetInfo ti, TargetInfo[string] targets, size_t level = 0)
+		static void configureDependencies(const scope ref TargetInfo ti, TargetInfo[string] targets, size_t level = 0)
 		{
 			// do not use `visited` here as dependencies must inherit
 			// configurations from *all* of their parents
@@ -527,14 +527,14 @@
 		ti.pack.metadataCache = cache;
 	}
 
-	private static void mergeFromDependent(in ref BuildSettings parent, ref BuildSettings child)
+	private static void mergeFromDependent(const scope ref BuildSettings parent, ref BuildSettings child)
 	{
 		child.addVersions(parent.versions);
 		child.addDebugVersions(parent.debugVersions);
 		child.addOptions(BuildOptions(parent.options & inheritedBuildOptions));
 	}
 
-	private static void mergeFromDependency(in ref BuildSettings child, ref BuildSettings parent, in ref BuildPlatform platform)
+	private static void mergeFromDependency(const scope ref BuildSettings child, ref BuildSettings parent, const scope ref BuildPlatform platform)
 	{
 		import dub.compilers.utils : isLinkerFile;
 
diff --git a/source/dub/recipe/io.d b/source/dub/recipe/io.d
index c66072e..994b3da 100644
--- a/source/dub/recipe/io.d
+++ b/source/dub/recipe/io.d
@@ -128,7 +128,7 @@
 
 	Note that the file extension must be either "json" or "sdl".
 */
-void writePackageRecipe(string filename, in ref PackageRecipe recipe)
+void writePackageRecipe(string filename, const scope ref PackageRecipe recipe)
 {
 	import dub.internal.vibecompat.core.file : openFile, FileMode;
 	auto f = openFile(filename, FileMode.createTrunc);
@@ -137,7 +137,7 @@
 }
 
 /// ditto
-void writePackageRecipe(NativePath filename, in ref PackageRecipe recipe)
+void writePackageRecipe(NativePath filename, const scope ref PackageRecipe recipe)
 {
 	writePackageRecipe(filename.toNativeString, recipe);
 }
@@ -147,7 +147,7 @@
 	The extension of the supplied `filename` must be either "json" or "sdl".
 	The output format is chosen accordingly.
 */
-void serializePackageRecipe(R)(ref R dst, in ref PackageRecipe recipe, string filename)
+void serializePackageRecipe(R)(ref R dst, const scope ref PackageRecipe recipe, string filename)
 {
 	import std.algorithm : endsWith;
 	import dub.internal.vibecompat.data.json : writeJsonString;
@@ -160,4 +160,3 @@
 		toSDL(recipe).toSDLDocument(dst);
 	else assert(false, "writePackageRecipe called with filename with unknown extension: "~filename);
 }
-
diff --git a/source/dub/recipe/json.d b/source/dub/recipe/json.d
index 791d485..54486c7 100644
--- a/source/dub/recipe/json.d
+++ b/source/dub/recipe/json.d
@@ -73,7 +73,7 @@
 		recipe.parseSubPackages(fullname, ps.opt!(Json[]));
 }
 
-Json toJson(in ref PackageRecipe recipe)
+Json toJson(const scope ref PackageRecipe recipe)
 {
 	auto ret = recipe.buildSettings.toJson();
 	ret["name"] = recipe.name;
@@ -152,7 +152,7 @@
 	config.buildSettings.parseJson(json, package_name);
 }
 
-private Json toJson(in ref ConfigurationInfo config)
+private Json toJson(const scope ref ConfigurationInfo config)
 {
 	auto ret = config.buildSettings.toJson();
 	ret["name"] = config.name;
@@ -245,7 +245,7 @@
 	}
 }
 
-private Json toJson(in ref BuildSettingsTemplate bs)
+private Json toJson(const scope ref BuildSettingsTemplate bs)
 {
 	auto ret = Json.emptyObject;
 	if( bs.dependencies !is null ){
@@ -302,7 +302,7 @@
 		tr.addRequirement(name, value.get!string);
 }
 
-private Json toJson(in ref ToolchainRequirements tr)
+private Json toJson(const scope ref ToolchainRequirements tr)
 {
 	auto ret = Json.emptyObject;
 	if (tr.dub != Dependency.any) ret["dub"] = serializeToJson(tr.dub);
diff --git a/source/dub/recipe/packagerecipe.d b/source/dub/recipe/packagerecipe.d
index a879991..e03fa92 100644
--- a/source/dub/recipe/packagerecipe.d
+++ b/source/dub/recipe/packagerecipe.d
@@ -341,7 +341,7 @@
 	}
 }
 
-package(dub) void checkPlatform(in ref ToolchainRequirements tr, BuildPlatform platform, string package_name)
+package(dub) void checkPlatform(const scope ref ToolchainRequirements tr, BuildPlatform platform, string package_name)
 {
 	import dub.compilers.utils : dmdLikeVersionToSemverLike;
 	import std.algorithm.iteration : map;
diff --git a/source/dub/recipe/sdl.d b/source/dub/recipe/sdl.d
index d13d4c8..cc6ab55 100644
--- a/source/dub/recipe/sdl.d
+++ b/source/dub/recipe/sdl.d
@@ -88,7 +88,7 @@
 	}
 }
 
-Tag toSDL(in ref PackageRecipe recipe)
+Tag toSDL(const scope ref PackageRecipe recipe)
 {
 	Tag ret = new Tag;
 	void add(T)(string field, T value) { ret.add(new Tag(null, field, [Value(value)])); }
@@ -217,7 +217,7 @@
 	}
 }
 
-private Tag toSDL(in ref ConfigurationInfo config)
+private Tag toSDL(const scope ref ConfigurationInfo config)
 {
 	auto ret = new Tag(null, "configuration", [Value(config.name)]);
 	if (config.platforms.length) ret.add(new Tag(null, "platforms", config.platforms[].map!(p => Value(p)).array));
@@ -225,7 +225,7 @@
 	return ret;
 }
 
-private Tag[] toSDL(in ref BuildSettingsTemplate bs)
+private Tag[] toSDL(const scope ref BuildSettingsTemplate bs)
 {
 	Tag[] ret;
 	void add(string name, string value, string namespace = null) { ret ~= new Tag(namespace, name, [Value(value)]); }