diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index c35f987ab89..afc3b7f8772 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -15433,7 +15433,7 @@ fold_read_from_constant_string (tree exp)
       if (string
 	  && TYPE_MODE (TREE_TYPE (exp)) == TYPE_MODE (TREE_TYPE (TREE_TYPE (string)))
 	  && TREE_CODE (string) == STRING_CST
-	  && TREE_CODE (index) == INTEGER_CST
+	  && tree_fits_uhwi_p (index)
 	  && compare_tree_int (index, TREE_STRING_LENGTH (string)) < 0
 	  && is_int_mode (TYPE_MODE (TREE_TYPE (TREE_TYPE (string))),
 			  &char_mode)
diff --git a/gcc/testsuite/gfortran.dg/pr99204.f90 b/gcc/testsuite/gfortran.dg/pr99204.f90
new file mode 100644
index 00000000000..9b6f27fa3d2
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr99204.f90
@@ -0,0 +1,10 @@
+! PR tree-optimization/99204
+! { dg-do compile }
+! { dg-options "-O2 -w" }
+
+program pr99204
+  character :: c
+  integer :: i = -12345678
+  c = 'abc'(i:i)
+  print *, c
+end