diff --git a/src/cmd/compile/internal/noder/helpers.go b/src/cmd/compile/internal/noder/helpers.go
index 117abe603d..1f7b497599 100644
--- a/src/cmd/compile/internal/noder/helpers.go
+++ b/src/cmd/compile/internal/noder/helpers.go
@@ -87,13 +87,14 @@ func idealType(tv syntax.TypeAndValue) types2.Type {
 			// ok; can appear in type switch case clauses
 			// TODO(mdempsky): Handle as part of type switches instead?
 		case types2.UntypedInt, types2.UntypedFloat, types2.UntypedComplex:
-			// Untyped rhs of non-constant shift, e.g. x << 1.0.
-			// If we have a constant value, it must be an int >= 0.
+			typ = types2.Typ[types2.Uint]
 			if tv.Value != nil {
 				s := constant.ToInt(tv.Value)
-				assert(s.Kind() == constant.Int && constant.Sign(s) >= 0)
+				assert(s.Kind() == constant.Int)
+				if constant.Sign(s) < 0 {
+					typ = types2.Typ[types2.Int]
+				}
 			}
-			typ = types2.Typ[types2.Uint]
 		case types2.UntypedBool:
 			typ = types2.Typ[types2.Bool] // expression in "if" or "for" condition
 		case types2.UntypedString:
diff --git a/src/cmd/compile/internal/noder/reader.go b/src/cmd/compile/internal/noder/reader.go
index 1c0d0a9acc..3cd7b7c683 100644
--- a/src/cmd/compile/internal/noder/reader.go
+++ b/src/cmd/compile/internal/noder/reader.go
@@ -2233,6 +2233,13 @@ func (r *reader) expr() (res ir.Node) {
 		switch op {
 		case ir.OANDAND, ir.OOROR:
 			return typecheck.Expr(ir.NewLogicalExpr(pos, op, x, y))
+		case ir.OLSH, ir.ORSH:
+			// Untyped rhs of non-constant shift, e.g. x << 1.0.
+			// If we have a constant value, it must be an int >= 0.
+			if ir.IsConstNode(y) {
+				val := constant.ToInt(y.Val())
+				assert(val.Kind() == constant.Int && constant.Sign(val) >= 0)
+			}
 		}
 		return typecheck.Expr(ir.NewBinaryExpr(pos, op, x, y))
 
diff --git a/test/range3.go b/test/range3.go
index 613d7a53f6..51ed2eeb78 100644
--- a/test/range3.go
+++ b/test/range3.go
@@ -68,6 +68,14 @@ func testint3() {
 	}
 }
 
+// Issue #63378.
+func testint4() {
+	for i := range -1 {
+		_ = i
+		panic("must not be executed")
+	}
+}
+
 // test range over functions
 
 var gj int
@@ -377,6 +385,7 @@ func main() {
 	testint1()
 	testint2()
 	testint3()
+	testint4()
 	testfunc0()
 	testfunc1()
 	testfunc2()