diff --git a/src/tests/helpers/joinir_env.rs b/src/tests/helpers/joinir_env.rs
index ce273faf..69538250 100644
--- a/src/tests/helpers/joinir_env.rs
+++ b/src/tests/helpers/joinir_env.rs
@@ -25,3 +25,14 @@ pub fn clear_joinir_flags() {
 pub fn is_experiment_enabled() -> bool {
     std::env::var("NYASH_JOINIR_EXPERIMENT").ok().as_deref() == Some("1")
 }
+
+/// Phase 72-B: HAKO_JOINIR_IF_SELECT SSOT ヘルパー
+/// IfSelect/JoinIR If分岐選択モードをONにする
+pub fn set_if_select_on() {
+    std::env::set_var("HAKO_JOINIR_IF_SELECT", "1");
+}
+
+/// IfSelect/JoinIR If分岐選択モードをOFFにする
+pub fn set_if_select_off() {
+    std::env::remove_var("HAKO_JOINIR_IF_SELECT");
+}
diff --git a/src/tests/mir_joinir_if_select.rs b/src/tests/mir_joinir_if_select.rs
index 5af017c1..339d9ccb 100644
--- a/src/tests/mir_joinir_if_select.rs
+++ b/src/tests/mir_joinir_if_select.rs
@@ -7,6 +7,7 @@ mod tests {
     use crate::mir::join_ir::lowering::try_lower_if_to_joinir;
     use crate::mir::join_ir::JoinInst;
     use crate::mir::{BasicBlock, BasicBlockId, MirFunction, MirInstruction, MirModule, ValueId};
+    use crate::tests::helpers::joinir_env;
     use std::collections::BTreeMap;
     use std::env;
 
@@ -148,7 +149,7 @@ mod tests {
         clear_joinir_flags();
 
         // ==== 1. Simple pattern (env ON) ====
-        std::env::set_var("HAKO_JOINIR_IF_SELECT", "1");
+        joinir_env::set_if_select_on();
 
         let func = create_simple_pattern_mir();
         let entry_block = func.entry_block;
@@ -205,7 +206,7 @@ mod tests {
 
         // ==== 3. Disabled by default (env OFF) ====
         set_core_off();
-        std::env::remove_var("HAKO_JOINIR_IF_SELECT");
+        joinir_env::set_if_select_off();
 
         let func = create_simple_pattern_mir();
         let entry_block = func.entry_block;
@@ -219,7 +220,7 @@ mod tests {
         eprintln!("✅ If/Select lowering correctly disabled by default");
 
         // ==== 4. Wrong function name (env ON) ====
-        std::env::set_var("HAKO_JOINIR_IF_SELECT", "1");
+        joinir_env::set_if_select_on();
 
         let mut func = create_simple_pattern_mir();
         func.signature.name = "WrongName.test/1".to_string();
@@ -545,7 +546,7 @@ mod tests {
         use crate::mir::join_ir::JoinInst;
 
         let _env = strict_if_env_guard();
-        std::env::set_var("HAKO_JOINIR_IF_SELECT", "1");
+        joinir_env::set_if_select_on();
 
         let func = create_if_merge_simple_pattern_mir();
         let entry_block = func.entry_block;
@@ -578,7 +579,7 @@ mod tests {
             panic!("Expected JoinInst::IfMerge, got {:?}", result);
         }
 
-        std::env::remove_var("HAKO_JOINIR_IF_SELECT");
+        joinir_env::set_if_select_off();
     }
 
     /// Phase 33-7: Test IfMerge lowering for 3-variable pattern
@@ -587,7 +588,7 @@ mod tests {
         use crate::mir::join_ir::JoinInst;
 
         let _env = strict_if_env_guard();
-        std::env::set_var("HAKO_JOINIR_IF_SELECT", "1");
+        joinir_env::set_if_select_on();
 
         let func = create_if_merge_multiple_pattern_mir();
         let entry_block = func.entry_block;
@@ -620,7 +621,7 @@ mod tests {
             panic!("Expected JoinInst::IfMerge, got {:?}", result);
         }
 
-        std::env::remove_var("HAKO_JOINIR_IF_SELECT");
+        joinir_env::set_if_select_off();
     }
 
     /// Phase 63-2: Helper to create a simple pattern MIR with Const instructions
@@ -683,7 +684,7 @@ mod tests {
         use crate::mir::MirType;
 
         let _env = strict_if_env_guard();
-        std::env::set_var("HAKO_JOINIR_IF_SELECT", "1");
+        joinir_env::set_if_select_on();
 
         let func = create_simple_pattern_mir_with_const();
         let entry_block = func.entry_block;
@@ -708,7 +709,7 @@ mod tests {
             panic!("Expected Select instruction with type_hint");
         }
 
-        std::env::remove_var("HAKO_JOINIR_IF_SELECT");
+        joinir_env::set_if_select_off();
     }
 
     /// Phase 63-6-4: A/B テスト - Route A (legacy) vs Route B (type hint)
@@ -721,7 +722,7 @@ mod tests {
         use crate::mir::MirType;
 
         let _env = strict_if_env_guard();
-        std::env::set_var("HAKO_JOINIR_IF_SELECT", "1");
+        joinir_env::set_if_select_on();
 
         // P1 Simple pattern で Select 生成
         let func = create_simple_pattern_mir_with_const();
@@ -748,7 +749,7 @@ mod tests {
         eprintln!("✅ Phase 63-6-4 Step 2: P1 function name filter: IfSelectTest.* ✓");
         eprintln!("✅ Phase 63-6-4: A/B test passed - JoinIR type hint available for lifecycle.rs");
 
-        std::env::remove_var("HAKO_JOINIR_IF_SELECT");
+        joinir_env::set_if_select_off();
     }
 
     /// Phase 64-2-2: A/B テスト - P2 IfMerge Simple 型ヒント検証