diff --git a/source/dpp/runtime/app.d b/source/dpp/runtime/app.d
index 787f40f0..80733948 100644
--- a/source/dpp/runtime/app.d
+++ b/source/dpp/runtime/app.d
@@ -11,9 +11,10 @@ import dpp.from;
 void run(in from!"dpp.runtime.options".Options options) @safe {
     import std.stdio: File;
     import std.exception: enforce;
-    import std.process: execute;
+    import std.process: spawnProcess, wait;
     import std.array: join;
     import std.file: remove;
+    import std.conv : text;
 
     foreach(dppFileName; options.dppFileNames)
         preprocess!File(options, dppFileName, options.toDFileName(dppFileName));
@@ -21,12 +22,12 @@ void run(in from!"dpp.runtime.options".Options options) @safe {
     if(options.preprocessOnly) return;
 
     const args = options.dlangCompiler ~ options.dlangCompilerArgs;
-    const res = execute(args);
-    enforce(res.status == 0, "Could not execute `" ~ args.join(" ") ~ "`:\n" ~ res.output);
+    const status = spawnProcess(args).wait();
     if(!options.keepDlangFiles) {
         foreach(fileName; options.dFileNames)
             remove(fileName);
     }
+    enforce(status == 0, "Executing `" ~ args.join(" ") ~ "` failed with exit code\n" ~ status.text);
 }
 
 
@@ -108,7 +109,7 @@ private string preamble() @safe pure {
         import core.stdc.config;
         import core.stdc.stdarg: va_list;
         struct __locale_data { int dummy; }  // FIXME
-        #define __gnuc_va_list va_list
+        } ~ "#define __gnuc_va_list va_list\n" ~ q{
         alias _Bool = bool;
 
         struct dpp {
diff --git a/source/dpp/runtime/options.d b/source/dpp/runtime/options.d
index 097f10da..79f93438 100644
--- a/source/dpp/runtime/options.d
+++ b/source/dpp/runtime/options.d
@@ -35,6 +35,7 @@ struct Options {
         import std.algorithm: map, filter, canFind, startsWith;
         import std.array: array;
         import std.conv: text;
+        import dpp.runtime.response : response_expand;
 
         parseArgs(args);
         if(earlyExit) return;
@@ -46,23 +47,15 @@ struct Options {
         else
             enforce(args.length >= 2, "Not enough arguments\n" ~ usage);
 
+        args = response_expand(args);
+
         dppFileNames = args.filter!(a => a.extension == ".dpp").array;
-        enforce(dppFileNames.length != 0, "No .dpp input file specified\n" ~ usage);
 
         // Remove the name of this binary and the name of the .dpp input file from args
         // so that a D compiler can use the remaining entries.
-        dlangCompilerArgs =
-            args[1..$].filter!(a => a.extension != ".dpp").array ~
-            dFileNames;
-
-        // if no -of option is given, default to the name of the .dpp file
-        if(!dlangCompilerArgs.canFind!(a => a.startsWith("-of")) && !dlangCompilerArgs.canFind("-c"))
-            dlangCompilerArgs ~= "-of" ~
-                args.
-                filter!(a => a.extension == ".dpp" || a.extension == ".d")
-                .front
-                .stripExtension
-                ~ exeExtension;
+        dlangCompilerArgs = args[1..$]
+		    .map!(a => a.extension == ".dpp" ? toDFileName(a) : a)
+		    .array;
 
         includePaths = systemPaths ~ includePaths;
     }
diff --git a/source/dpp/runtime/response.d b/source/dpp/runtime/response.d
new file mode 100644
index 00000000..06485aa1
--- /dev/null
+++ b/source/dpp/runtime/response.d
@@ -0,0 +1,206 @@
+module dpp.runtime.response;
+import core.stdc.stdio;
+import core.stdc.stdlib;
+import core.stdc.string;
+
+/// wrapper to make response_expand usable
+/// with strings. Yes, it allocates a lot.
+string[] response_expand(string[] args) @trusted
+{
+    import std.algorithm : map;
+    import std.array : array;
+    import std.string : fromStringz;
+    import std.exception : enforce;
+
+    auto cargs = args
+            .map!toConstStringz
+            .array;
+    enforce(!response_expand(cargs), "expanding args failed");
+    return cargs
+        .map!(s => s.fromStringz.idup)
+        .array;
+}
+
+const(char)* toConstStringz(string s) @safe
+{
+    auto r = new char[](s.length + 1);
+    size_t i = 0;
+    while (i < s.length)
+    {
+        r[i] = s[i];
+        if (r[i] == '\0')
+            break;
+        ++i;
+    }
+    if (i == s.length)
+        r[i] = '\0';
+    return &r[0];
+}
+
+// ported from dmd's function of the same name.
+// only modifications are to use builtin arrays
+// and phobos in place of dmd's bespoke types
+bool response_expand(ref const(char)*[] args)
+{
+    import std.algorithm : remove;
+    import std.file : readText;
+    import std.array : insertInPlace;
+
+    const(char)* cp;
+    int recurse = 0;
+    for (size_t i = 0; i < args.length;)
+    {
+        cp = args[i];
+        if (*cp != '@')
+        {
+            ++i;
+            continue;
+        }
+        args = args.remove(i);
+        char* buffer;
+        char* bufend;
+        cp++;
+        if (auto p = getenv(cp))
+        {
+            buffer = strdup(p);
+            if (!buffer)
+                goto noexpand;
+            bufend = buffer + strlen(buffer);
+        }
+        else
+        {
+            auto s = cp[0 .. strlen(cp)].readText!(char[]);
+            buffer = s.ptr;
+            bufend = buffer + s.length;
+        }
+        // The logic of this should match that in setargv()
+        int comment = 0;
+        for (auto p = buffer; p < bufend; p++)
+        {
+            char* d;
+            char c, lastc;
+            ubyte instring;
+            int num_slashes, non_slashes;
+            switch (*p)
+            {
+            case 26:
+                /* ^Z marks end of file      */
+                goto L2;
+            case 0xD:
+            case '\n':
+                if (comment)
+                {
+                    comment = 0;
+                }
+                goto case;
+            case 0:
+            case ' ':
+            case '\t':
+                continue;
+                // scan to start of argument
+            case '#':
+                comment = 1;
+                continue;
+            case '@':
+                if (comment)
+                {
+                    continue;
+                }
+                recurse = 1;
+                goto default;
+            default:
+                /* start of new argument   */
+                if (comment)
+                {
+                    continue;
+                }
+                args.insertInPlace(i, p);
+                ++i;
+                instring = 0;
+                c = 0;
+                num_slashes = 0;
+                for (d = p; 1; p++)
+                {
+                    lastc = c;
+                    if (p >= bufend)
+                    {
+                        *d = 0;
+                        goto L2;
+                    }
+                    c = *p;
+                    switch (c)
+                    {
+                    case '"':
+                        /*
+                         Yes this looks strange,but this is so that we are
+                         MS Compatible, tests have shown that:
+                         \\\\"foo bar"  gets passed as \\foo bar
+                         \\\\foo  gets passed as \\\\foo
+                         \\\"foo gets passed as \"foo
+                         and \"foo gets passed as "foo in VC!
+                         */
+                        non_slashes = num_slashes % 2;
+                        num_slashes = num_slashes / 2;
+                        for (; num_slashes > 0; num_slashes--)
+                        {
+                            d--;
+                            *d = '\0';
+                        }
+                        if (non_slashes)
+                        {
+                            *(d - 1) = c;
+                        }
+                        else
+                        {
+                            instring ^= 1;
+                        }
+                        break;
+                    case 26:
+                        *d = 0; // terminate argument
+                        goto L2;
+                    case 0xD:
+                        // CR
+                        c = lastc;
+                        continue;
+                        // ignore
+                    case '@':
+                        recurse = 1;
+                        goto Ladd;
+                    case ' ':
+                    case '\t':
+                        if (!instring)
+                        {
+                        case '\n':
+                        case 0:
+                            *d = 0; // terminate argument
+                            goto Lnextarg;
+                        }
+                        goto default;
+                    default:
+                    Ladd:
+                        if (c == '\\')
+                            num_slashes++;
+                        else
+                            num_slashes = 0;
+                        *d++ = c;
+                        break;
+                    }
+                }
+                break;
+            }
+        Lnextarg:
+        }
+    L2:
+    }
+    if (recurse)
+    {
+        /* Recursively expand @filename   */
+        if (response_expand(args))
+            goto noexpand;
+    }
+    return false; /* success         */
+noexpand:
+    /* error         */
+    /* BUG: any file buffers are not free'd   */
+    return true;
+}
diff --git a/tests/it/issues.d b/tests/it/issues.d
index e9415d62..e4a710be 100644
--- a/tests/it/issues.d
+++ b/tests/it/issues.d
@@ -165,22 +165,6 @@ import it;
     );
 }
 
-@Tags("issue")
-@("14")
-@safe unittest {
-    import dpp.runtime.options: Options;
-    with(immutable IncludeSandbox()) {
-
-        writeFile("foo.h",
-                  q{
-                      typedef int foo;
-                  });
-
-        runPreprocessOnly("foo.h").shouldThrowWithMessage(
-            "No .dpp input file specified\n" ~ Options.usage);
-    }
-}
-
 @Tags("issue", "preprocessor")
 @("22.0")
 @safe unittest {
diff --git a/tests/test_main.d b/tests/test_main.d
index 12c038fc..dee81996 100644
--- a/tests/test_main.d
+++ b/tests/test_main.d
@@ -10,6 +10,7 @@ int main(string[] args) {
 
         // unit tests
         "ut.type",
+        "ut.response",
 
         "it.issues",
 
diff --git a/tests/ut/response.d b/tests/ut/response.d
new file mode 100644
index 00000000..947c3f42
--- /dev/null
+++ b/tests/ut/response.d
@@ -0,0 +1,20 @@
+module ut.response;
+
+import dpp.test;
+import dpp.runtime.response;
+
+@("toConstStringz")
+@safe unittest
+{
+    import std.algorithm : until;
+    foreach (s; [null, "", "a", "áåâà", "fd\0fds"])
+    {
+        // make sure we're not being saved by string
+        // literals being null-terminated
+        auto cstr = (s ~ 'a')[0 .. $ - 1]
+            .toConstStringz;
+        static assert(is(typeof(cstr) == const(char)*));
+        (() @trusted => cstr[0 .. s.length + 1])().until('\0')
+            .shouldEqual(s.until('\0'));
+    }
+}