diff --git a/src/cmd/compile/internal/gc/pgen.go b/src/cmd/compile/internal/gc/pgen.go
index 71d9b8f9e3..06b7e5a691 100644
--- a/src/cmd/compile/internal/gc/pgen.go
+++ b/src/cmd/compile/internal/gc/pgen.go
@@ -207,7 +207,6 @@ func (s *ssafn) AllocFrame(f *ssa.Func) {
 		if ls, ok := l.(ssa.LocalSlot); ok {
 			ls.N.(*Node).SetUsed(true)
 		}
-
 	}
 
 	scratchUsed := false
@@ -215,7 +214,11 @@ func (s *ssafn) AllocFrame(f *ssa.Func) {
 		for _, v := range b.Values {
 			switch a := v.Aux.(type) {
 			case *ssa.ArgSymbol:
-				a.Node.(*Node).SetUsed(true)
+				n := a.Node.(*Node)
+				// Don't modify nodfp; it is a global.
+				if n != nodfp {
+					n.SetUsed(true)
+				}
 			case *ssa.AutoSymbol:
 				a.Node.(*Node).SetUsed(true)
 			}
diff --git a/src/cmd/compile/internal/gc/universe.go b/src/cmd/compile/internal/gc/universe.go
index fea0103b33..50f7335cd0 100644
--- a/src/cmd/compile/internal/gc/universe.go
+++ b/src/cmd/compile/internal/gc/universe.go
@@ -463,4 +463,5 @@ func finishUniverse() {
 	nodfp = newname(lookup(".fp"))
 	nodfp.Type = Types[TINT32]
 	nodfp.Class = PPARAM
+	nodfp.SetUsed(true)
 }