diff --git a/dmd/mtype.c b/dmd/mtype.c
index 5bcaa9e3..f8ec367a 100644
--- a/dmd/mtype.c
+++ b/dmd/mtype.c
@@ -2951,6 +2951,11 @@ Type *TypeFunction::semantic(Loc loc, Scope *sc)
 	{   Argument *arg = Argument::getNth(tf->parameters, i);
 	    Type *t;
 
+	    // each function needs its own copy of a tuple arg, since
+	    // they mustn't share arg flags like inreg, ...
+	    if (arg->type->ty == Ttuple)
+		arg->type = arg->type->syntaxCopy();
+
 	    tf->inuse++;
 	    arg->type = arg->type->semantic(loc,sc);
 	    if (tf->inuse == 1) tf->inuse--;
@@ -3466,7 +3471,7 @@ L1:
 	    }
 	}
 	if (t->ty == Ttuple)
-	    *pt = t->syntaxCopy();
+	    *pt = t;
 	else
 	    *pt = t->merge();
     }
diff --git a/tests/mini/compile_delegatetuple.d b/tests/mini/compile_delegatetuple.d
new file mode 100644
index 00000000..2416c796
--- /dev/null
+++ b/tests/mini/compile_delegatetuple.d
@@ -0,0 +1,14 @@
+alias char[] string;
+template Unstatic(T) { alias T Unstatic; }
+template Unstatic(T: T[]) { alias T[] Unstatic; }
+template StupleMembers(T...) {
+  static if (T.length) {
+      const int id=T[0..$-1].length;
+      const string str=StupleMembers!(T[0..$-1]).str~"Unstatic!(T["~id.stringof~"]) _"~id.stringof~"; ";
+  } else const string str="";
+}
+
+struct Stuple(T...) {
+ mixin(StupleMembers!(T).str);
+}     
+Stuple!(string, void delegate(float)) foo;