diff --git a/src/hotspot/share/opto/inlinetypenode.cpp b/src/hotspot/share/opto/inlinetypenode.cpp
index 6e701a27599..68a664c23fe 100644
--- a/src/hotspot/share/opto/inlinetypenode.cpp
+++ b/src/hotspot/share/opto/inlinetypenode.cpp
@@ -865,6 +865,8 @@ Node* InlineTypeNode::emit_substitutability_check(GraphKit* kit, Node* lhs, Node
 
       Node* cur_lhs_field = cur_lhs->field_value(field_idx);
       Node* cur_rhs_field = cur_rhs->field_value(field_idx);
+      InlineTypeNode* cur_lhs_inline = cur_lhs_field->isa_InlineType();
+      InlineTypeNode* cur_rhs_inline = cur_rhs_field->isa_InlineType();
 
       Node* preprocess = emit_substitutability_check_pointer(kit, result, cur_lhs_field, cur_rhs_field);
       if (kit->stopped()) {
@@ -951,21 +953,30 @@ Node* InlineTypeNode::emit_substitutability_check(GraphKit* kit, Node* lhs, Node
       Node* vk_klass = igvn.makecon(vk_klass_type);
 
       // Both must be vk
-      Node* not_vk = kit->top();
-      cur_lhs_field = kit->gen_checkcast(cur_lhs_field, vk_klass, &not_vk);
-      if (!not_vk->is_top()) {
-        region->add_req(not_vk);
-        result->add_req(igvn.intcon(0));
+      // InlineTypeNodes need no (new) field loads, so we can use the uncasted value below.
+      if (cur_lhs_inline != nullptr && cur_lhs_inline->inline_klass() == vk) {
+        cur_lhs_field = cur_lhs_inline;
+      } else {
+        Node* not_vk = kit->top();
+        cur_lhs_field = kit->gen_checkcast(cur_lhs_field, vk_klass, &not_vk);
+        if (!not_vk->is_top()) {
+          region->add_req(not_vk);
+          result->add_req(igvn.intcon(0));
+        }
+        cur_lhs_field = InlineTypeNode::make_from_oop(kit, cur_lhs_field, vk);
       }
-      cur_lhs_field = InlineTypeNode::make_from_oop(kit, cur_lhs_field, vk);
 
-      not_vk = kit->top();
-      cur_rhs_field = kit->gen_checkcast(cur_rhs_field, vk_klass, &not_vk);
-      if (!not_vk->is_top()) {
-        region->add_req(not_vk);
-        result->add_req(igvn.intcon(0));
+      if (cur_rhs_inline != nullptr && cur_rhs_inline->inline_klass() == vk) {
+        cur_rhs_field = cur_rhs_inline;
+      } else {
+        Node* not_vk = kit->top();
+        cur_rhs_field = kit->gen_checkcast(cur_rhs_field, vk_klass, &not_vk);
+        if (!not_vk->is_top()) {
+          region->add_req(not_vk);
+          result->add_req(igvn.intcon(0));
+        }
+        cur_rhs_field = InlineTypeNode::make_from_oop(kit, cur_rhs_field, vk);
       }
-      cur_rhs_field = InlineTypeNode::make_from_oop(kit, cur_rhs_field, vk);
 
       if (!kit->stopped()) {
         // Push the expanded InlineTypeNodes for processing later
diff --git a/test/hotspot/jtreg/compiler/valhalla/inlinetypes/TestLWorld.java b/test/hotspot/jtreg/compiler/valhalla/inlinetypes/TestLWorld.java
index 71ece91bd46..ef64dc12e78 100644
--- a/test/hotspot/jtreg/compiler/valhalla/inlinetypes/TestLWorld.java
+++ b/test/hotspot/jtreg/compiler/valhalla/inlinetypes/TestLWorld.java
@@ -5479,4 +5479,36 @@ public static void testBadCastToInlineKlass_verifier() {
             // expected
         }
     }
+
+    // TODO 8376254: C1 bails out if the type of the nullable flat field is uninitialized
+    static ObjectHolderHolder objectHolderHolder = new ObjectHolderHolder();
+
+    static value class ObjectHolder {
+        Object obj = new Object();
+    }
+
+    static value class ObjectHolderHolder {
+        ObjectHolder objectHolder = new ObjectHolder();
+    }
+
+    // Test that acmp expansion works with field of exact Object type
+    @Test
+    @IR(failOn = {STATIC_CALL_OF_METHOD, "isSubstitutable.*"},
+        counts = {IRNode.ALLOC, "= 2"}) // The two Object allocations
+    static boolean testAcmp() {
+        Object lhs = null;
+        Object rhs = null;
+        for (int i = 0; i < 10; i++) {
+            if ((i & 1) == 0) {
+                lhs = new ObjectHolderHolder();
+                rhs = new ObjectHolderHolder();
+            }
+        }
+        return lhs == rhs;
+    }
+
+    @Run(test = "testAcmp")
+    public void runTestAcmp() {
+        Asserts.assertFalse(testAcmp());
+    }
 }
diff --git a/test/hotspot/jtreg/compiler/valhalla/inlinetypes/TestOptimizePtrCompare.java b/test/hotspot/jtreg/compiler/valhalla/inlinetypes/TestOptimizePtrCompare.java
index 3f5dca15f0f..df4b3d91f0b 100644
--- a/test/hotspot/jtreg/compiler/valhalla/inlinetypes/TestOptimizePtrCompare.java
+++ b/test/hotspot/jtreg/compiler/valhalla/inlinetypes/TestOptimizePtrCompare.java
@@ -164,6 +164,7 @@ static MyValue2 notInlined5(MyValue2 v) {
         return v;
     }
 
+    // TODO 8376254: C1 bails out if the type of the nullable flat field is uninitialized
     @Test(allowNotCompilable = true)
     @IR(applyIfAnd = {"InlineTypePassFieldsAsArgs", "true", "InlineTypeReturnedAsFields", "true"}, failOn = {IRNode.CMP_P_OR_N})
     @IR(applyIfAnd = {"InlineTypePassFieldsAsArgs", "false", "InlineTypeReturnedAsFields", "true"}, counts = {IRNode.CMP_P_OR_N, "4", IRNode.CMP_I, "2"})