diff --git a/gcc/fortran/io.c b/gcc/fortran/io.c
index 2a387535d05..5d444edccd7 100644
--- a/gcc/fortran/io.c
+++ b/gcc/fortran/io.c
@@ -1763,7 +1763,7 @@ resolve_tag_format (gfc_expr *e)
   if (e->ts.type != BT_CHARACTER)
     {
       if (e->ts.type == BT_DERIVED || e->ts.type == BT_CLASS
-	  || e->ts.type == BT_VOID)
+	  || e->ts.type == BT_VOID || e->ts.type == BT_UNKNOWN)
 	{
 	  gfc_error ("Non-character non-Hollerith in FORMAT tag at %L",
 		     &e->where);
diff --git a/gcc/testsuite/gfortran.dg/fmt_nonchar_3.f90 b/gcc/testsuite/gfortran.dg/fmt_nonchar_3.f90
new file mode 100644
index 00000000000..3b3c260ef7f
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/fmt_nonchar_3.f90
@@ -0,0 +1,7 @@
+! { dg-do compile }
+! PR fortran/101084
+
+program p
+  integer, parameter :: a(0) = 1
+  print int(a) ! { dg-error "Non-character non-Hollerith in FORMAT tag" }
+end