diff --git a/source/dub/compilers/compiler.d b/source/dub/compilers/compiler.d
index 950f29a..ff59b26 100644
--- a/source/dub/compilers/compiler.d
+++ b/source/dub/compilers/compiler.d
@@ -113,7 +113,7 @@
 	void invokeLinker(in BuildSettings settings, in BuildPlatform platform, string[] objects, void delegate(int, string) output_callback);
 
 	/// Convert linker flags to compiler format
-	string[] lflagsToDFlags(in string[] lflags) const;
+	string[] lflagsToDFlags(const string[] lflags) const;
 
 	/// Determines compiler version
 	string determineVersion(string compiler_binary, string verboseOutput);
diff --git a/source/dub/compilers/dmd.d b/source/dub/compilers/dmd.d
index 67db009..7c0bb32 100644
--- a/source/dub/compilers/dmd.d
+++ b/source/dub/compilers/dmd.d
@@ -398,7 +398,7 @@
 		invokeTool([platform.compilerBinary, "@"~res_file.toNativeString()], output_callback, env);
 	}
 
-	string[] lflagsToDFlags(in string[] lflags) const
+	string[] lflagsToDFlags(const string[] lflags) const
 	{
         return map!(f => "-L"~f)(lflags.filter!(f => f != "")()).array();
 	}
diff --git a/source/dub/compilers/gdc.d b/source/dub/compilers/gdc.d
index bce6259..fd47d01 100644
--- a/source/dub/compilers/gdc.d
+++ b/source/dub/compilers/gdc.d
@@ -236,7 +236,7 @@
 		invokeTool(args, output_callback, env);
 	}
 
-	string[] lflagsToDFlags(in string[] lflags) const
+	string[] lflagsToDFlags(const string[] lflags) const
 	{
 		string[] dflags;
 		foreach( f; lflags )
diff --git a/source/dub/compilers/ldc.d b/source/dub/compilers/ldc.d
index fc2791f..f37409d 100644
--- a/source/dub/compilers/ldc.d
+++ b/source/dub/compilers/ldc.d
@@ -268,7 +268,7 @@
 		invokeTool([platform.compilerBinary, "@"~res_file.toNativeString()], output_callback, env);
 	}
 
-	string[] lflagsToDFlags(in string[] lflags) const
+	string[] lflagsToDFlags(const string[] lflags) const
 	{
         return map!(f => "-L"~f)(lflags.filter!(f => f != "")()).array();
 	}