diff --git a/source/dub/compilers/compiler.d b/source/dub/compilers/compiler.d
index 9dde323..a3e721b 100644
--- a/source/dub/compilers/compiler.d
+++ b/source/dub/compilers/compiler.d
@@ -208,13 +208,13 @@
 
 	/// Replaces high level fields with low level fields and converts
 	/// dmd flags to compiler-specific flags
-	void prepareBuildSettings(ref BuildSettings settings, BuildSetting supported_fields = BuildSetting.all);
+	void prepareBuildSettings(ref BuildSettings settings, 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);
+	void extractBuildOptions(ref BuildSettings settings) const;
 
 	/// Adds the appropriate flag to set a target path
-	void setTarget(ref BuildSettings settings, in BuildPlatform platform);
+	void setTarget(ref BuildSettings settings, in BuildPlatform platform) const;
 
 	/// Invokes the compiler using the given flags
 	void invoke(in BuildSettings settings, in BuildPlatform platform, void delegate(int, string) output_callback);
diff --git a/source/dub/compilers/dmd.d b/source/dub/compilers/dmd.d
index 43bec23..ba9f84f 100644
--- a/source/dub/compilers/dmd.d
+++ b/source/dub/compilers/dmd.d
@@ -87,7 +87,7 @@
 		return build_platform;
 	}
 
-	void prepareBuildSettings(ref BuildSettings settings, BuildSetting fields = BuildSetting.all)
+	void prepareBuildSettings(ref BuildSettings settings, BuildSetting fields = BuildSetting.all) const
 	{
 		enforceBuildRequirements(settings);
 
@@ -137,7 +137,7 @@
 		assert(fields & BuildSetting.copyFiles);
 	}
 
-	void extractBuildOptions(ref BuildSettings settings)
+	void extractBuildOptions(ref BuildSettings settings) const
 	{
 		Appender!(string[]) newflags;
 		next_flag: foreach (f; settings.dflags) {
@@ -153,7 +153,7 @@
 		settings.dflags = newflags.data;
 	}
 
-	void setTarget(ref BuildSettings settings, in BuildPlatform platform)
+	void setTarget(ref BuildSettings settings, in BuildPlatform platform) const
 	{
 		final switch (settings.targetType) {
 			case TargetType.autodetect: assert(false, "Invalid target type: autodetect");
diff --git a/source/dub/compilers/gdc.d b/source/dub/compilers/gdc.d
index ac150bb..c213d38 100644
--- a/source/dub/compilers/gdc.d
+++ b/source/dub/compilers/gdc.d
@@ -90,7 +90,7 @@
 		return build_platform;
 	}
 
-	void prepareBuildSettings(ref BuildSettings settings, BuildSetting fields = BuildSetting.all)
+	void prepareBuildSettings(ref BuildSettings settings, BuildSetting fields = BuildSetting.all) const
 	{
 		enforceBuildRequirements(settings);
 
@@ -140,7 +140,7 @@
 		assert(fields & BuildSetting.copyFiles);
 	}
 
-	void extractBuildOptions(ref BuildSettings settings)
+	void extractBuildOptions(ref BuildSettings settings) const
 	{
 		Appender!(string[]) newflags;
 		next_flag: foreach (f; settings.dflags) {
@@ -156,7 +156,7 @@
 		settings.dflags = newflags.data;
 	}
 
-	void setTarget(ref BuildSettings settings, in BuildPlatform platform)
+	void setTarget(ref BuildSettings settings, in BuildPlatform platform) const
 	{
 		final switch (settings.targetType) {
 			case TargetType.autodetect: assert(false, "Invalid target type: autodetect");
diff --git a/source/dub/compilers/ldc.d b/source/dub/compilers/ldc.d
index dad1cf3..0c39cec 100644
--- a/source/dub/compilers/ldc.d
+++ b/source/dub/compilers/ldc.d
@@ -75,7 +75,7 @@
 		return build_platform;
 	}
 
-	void prepareBuildSettings(ref BuildSettings settings, BuildSetting fields = BuildSetting.all)
+	void prepareBuildSettings(ref BuildSettings settings, BuildSetting fields = BuildSetting.all) const
 	{
 		enforceBuildRequirements(settings);
 
@@ -127,7 +127,7 @@
 		assert(fields & BuildSetting.copyFiles);
 	}
 
-	void extractBuildOptions(ref BuildSettings settings)
+	void extractBuildOptions(ref BuildSettings settings) const
 	{
 		Appender!(string[]) newflags;
 		next_flag: foreach (f; settings.dflags) {
@@ -143,7 +143,7 @@
 		settings.dflags = newflags.data;
 	}
 
-	void setTarget(ref BuildSettings settings, in BuildPlatform platform)
+	void setTarget(ref BuildSettings settings, in BuildPlatform platform) const
 	{
 		final switch (settings.targetType) {
 			case TargetType.autodetect: assert(false, "Invalid target type: autodetect");