diff --git a/compile.c b/compile.c
index fb99826413..8f53955e74 100644
--- a/compile.c
+++ b/compile.c
@@ -2461,7 +2461,17 @@ iseq_set_sequence(rb_iseq_t *iseq, LINK_ANCHOR *const anchor)
                       case TS_IVC: /* inline ivar cache */
                         {
                             unsigned int ic_index = FIX2UINT(operands[j]);
-                            vm_ic_attr_index_initialize(((IVC)&body->is_entries[ic_index]), INVALID_SHAPE_ID);
+
+                            IVC cache = ((IVC)&body->is_entries[ic_index]);
+
+                            if (insn == BIN(setinstancevariable)) {
+                                cache->iv_set_name = SYM2ID(operands[j - 1]);
+                            }
+                            else {
+                                cache->iv_set_name = 0;
+                            }
+
+                            vm_ic_attr_index_initialize(cache, INVALID_SHAPE_ID);
                         }
                       case TS_ISE: /* inline storage entry: `once` insn */
                       case TS_ICVARC: /* inline cvar cache */
@@ -11529,7 +11539,17 @@ ibf_load_code(const struct ibf_load *load, rb_iseq_t *iseq, ibf_offset_t bytecod
                     code[code_index] = (VALUE)ic;
 
                     if (operand_type == TS_IVC) {
-                        vm_ic_attr_index_initialize(((IVC)code[code_index]), INVALID_SHAPE_ID);
+                        IVC cache = (IVC)ic;
+
+                        if (insn == BIN(setinstancevariable)) {
+                            ID iv_name = (ID)code[code_index - 1];
+                            cache->iv_set_name = iv_name;
+                        }
+                        else {
+                            cache->iv_set_name = 0;
+                        }
+
+                        vm_ic_attr_index_initialize(cache, INVALID_SHAPE_ID);
                     }
 
                 }
diff --git a/iseq.c b/iseq.c
index 381bf6ed20..869ed4da6a 100644
--- a/iseq.c
+++ b/iseq.c
@@ -2509,33 +2509,20 @@ rb_iseq_disasm(const rb_iseq_t *iseq)
 attr_index_t
 rb_estimate_iv_count(VALUE klass, const rb_iseq_t * initialize_iseq)
 {
-    bool calls_super = false;
-
     struct rb_id_table * iv_names = rb_id_table_create(0);
 
-    VALUE * code = ISEQ_BODY(initialize_iseq)->iseq_encoded;
+    for (unsigned int i = 0; i < ISEQ_BODY(initialize_iseq)->ivc_size; i++) {
+        IVC cache = (IVC)&ISEQ_BODY(initialize_iseq)->is_entries[i];
 
-    for (unsigned int i = 0; i < ISEQ_BODY(initialize_iseq)->iseq_size; ) {
-        VALUE insn = code[i];
-        int original_insn = rb_vm_insn_addr2insn((const void *)insn);
-
-        if (BIN(setinstancevariable) == original_insn) {
-            ID name = (ID)code[i + 1];
-            rb_id_table_insert(iv_names, name, Qtrue);
+        if (cache->iv_set_name) {
+            rb_id_table_insert(iv_names, cache->iv_set_name, Qtrue);
         }
-        else if (BIN(invokesuper) == original_insn) {
-            calls_super = true;
-        }
-
-        i += insn_len(original_insn);
     }
 
     attr_index_t count = (attr_index_t)rb_id_table_size(iv_names);
 
-    if (calls_super) {
-        VALUE superclass = rb_class_superclass(klass);
-        count += RCLASS_EXT(superclass)->max_iv_count;
-    }
+    VALUE superclass = rb_class_superclass(klass);
+    count += RCLASS_EXT(superclass)->max_iv_count;
 
     rb_id_table_free(iv_names);
 
diff --git a/mjit_c.rb b/mjit_c.rb
index e4933c3458..39ca89a0ea 100644
--- a/mjit_c.rb
+++ b/mjit_c.rb
@@ -310,6 +310,7 @@ module RubyVM::MJIT
     @iseq_inline_iv_cache_entry ||= CType::Struct.new(
       "iseq_inline_iv_cache_entry", Primitive.cexpr!("SIZEOF(struct iseq_inline_iv_cache_entry)"),
       value: [CType::Immediate.parse("uintptr_t"), Primitive.cexpr!("OFFSETOF((*((struct iseq_inline_iv_cache_entry *)NULL)), value)")],
+      iv_set_name: [self.ID, Primitive.cexpr!("OFFSETOF((*((struct iseq_inline_iv_cache_entry *)NULL)), iv_set_name)")],
     )
   end
 
diff --git a/vm_core.h b/vm_core.h
index a996c5b835..65f2741219 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -275,6 +275,7 @@ struct iseq_inline_constant_cache {
 
 struct iseq_inline_iv_cache_entry {
     uintptr_t value; // attr_index in lower bits, dest_shape_id in upper bits
+    ID iv_set_name;
 };
 
 struct iseq_inline_cvar_cache_entry {
diff --git a/yjit/src/cruby_bindings.inc.rs b/yjit/src/cruby_bindings.inc.rs
index 470b6d0a5b..1555196a06 100644
--- a/yjit/src/cruby_bindings.inc.rs
+++ b/yjit/src/cruby_bindings.inc.rs
@@ -853,6 +853,7 @@ pub struct iseq_inline_constant_cache {
 #[derive(Debug, Copy, Clone)]
 pub struct iseq_inline_iv_cache_entry {
     pub value: usize,
+    pub iv_set_name: ID,
 }
 #[repr(C)]
 #[derive(Debug, Copy, Clone)]