diff --git a/gcc/c-family/c-common.cc b/gcc/c-family/c-common.cc
index dc67562ce92..e15eff698df 100644
--- a/gcc/c-family/c-common.cc
+++ b/gcc/c-family/c-common.cc
@@ -8082,6 +8082,12 @@ atomic_bitint_fetch_using_cas_loop (location_t loc,
   tree lhs_addr = (*orig_params)[0];
   tree val = convert (nonatomic_lhs_type, (*orig_params)[1]);
   tree model = convert (integer_type_node, (*orig_params)[2]);
+  if (!c_dialect_cxx ())
+    {
+      lhs_addr = c_fully_fold (lhs_addr, false, NULL);
+      val = c_fully_fold (val, false, NULL);
+      model = c_fully_fold (model, false, NULL);
+    }
   if (TREE_SIDE_EFFECTS (lhs_addr))
     {
       tree var = create_tmp_var_raw (TREE_TYPE (lhs_addr));
diff --git a/gcc/testsuite/gcc.dg/bitint-77.c b/gcc/testsuite/gcc.dg/bitint-77.c
new file mode 100644
index 00000000000..0125f1e9fb3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/bitint-77.c
@@ -0,0 +1,25 @@
+/* PR c/113518 */
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-O2 -std=c23" } */
+
+#if __BITINT_MAXWIDTH__ >= 607
+_BitInt(607) v;
+#else
+_BitInt(63) v;
+#endif
+
+void
+foo (void)
+{
+  __atomic_fetch_or (&v, 1 << 31, __ATOMIC_RELAXED);
+}
+
+#if __BITINT_MAXWIDTH__ >= 16321
+_BitInt(16321) w;
+
+void
+bar (void)
+{
+  __atomic_fetch_add (&w, 1 << 31, __ATOMIC_SEQ_CST);
+}
+#endif