diff --git a/src/go/types/builtins.go b/src/go/types/builtins.go
index 0082be9e2e..fc4db4513b 100644
--- a/src/go/types/builtins.go
+++ b/src/go/types/builtins.go
@@ -434,7 +434,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			return
 		}
 		if nargs < min || min+1 < nargs {
-			check.errorf(call.Pos(), "%s expects %d or %d arguments; found %d", call, min, min+1, nargs)
+			check.errorf(call.Pos(), "%v expects %d or %d arguments; found %d", call, min, min+1, nargs)
 			return
 		}
 		var sizes []int64 // constant integer arguments, if any
@@ -595,7 +595,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			return
 		}
 		if !constant.BoolVal(x.val) {
-			check.errorf(call.Pos(), "%s failed", call)
+			check.errorf(call.Pos(), "%v failed", call)
 			// compile-time assertion failure - safe to continue
 		}
 		// result is constant - no need to record signature