diff --git a/examples/chip-tool/commands/tests/Commands.h b/examples/chip-tool/commands/tests/Commands.h
index 807a9bbe4e4f37..c8e5b1cd4aef23 100644
--- a/examples/chip-tool/commands/tests/Commands.h
+++ b/examples/chip-tool/commands/tests/Commands.h
@@ -24,7 +24,7 @@
 class TestCluster : public TestCommand
 {
 public:
-    TestCluster() : TestCommand("TestCluster") {}
+    TestCluster() : TestCommand("TestCluster"), mTestIndex(0) {}
 
     /////////// TestCommand Interface /////////
     CHIP_ERROR NextTest() override
@@ -37,7 +37,11 @@ class TestCluster : public TestCommand
             SetCommandExitStatus(true);
         }
 
-        switch (mTestIndex)
+        // Ensure we increment mTestIndex before we start running the relevant
+        // command.  That way if we lose the timeslice after we send the message
+        // but before our function call returns, we won't end up with an
+        // incorrect mTestIndex value observed when we get the response.
+        switch (mTestIndex++)
         {
         case 0:
             err = TestSendClusterTestClusterCommandTest_0();
@@ -55,7 +59,6 @@ class TestCluster : public TestCommand
             err = TestSendClusterTestClusterCommandReadAttribute_4();
             break;
         }
-        mTestIndex++;
 
         if (CHIP_NO_ERROR != err)
         {
@@ -67,8 +70,8 @@ class TestCluster : public TestCommand
     }
 
 private:
-    uint16_t mTestIndex = 0;
-    uint16_t mTestCount = 5;
+    std::atomic_uint16_t mTestIndex;
+    const uint16_t mTestCount = 5;
 
     //
     // Tests methods
@@ -437,7 +440,7 @@ class TestCluster : public TestCommand
 class OnOffCluster : public TestCommand
 {
 public:
-    OnOffCluster() : TestCommand("OnOffCluster") {}
+    OnOffCluster() : TestCommand("OnOffCluster"), mTestIndex(0) {}
 
     /////////// TestCommand Interface /////////
     CHIP_ERROR NextTest() override
@@ -450,7 +453,11 @@ class OnOffCluster : public TestCommand
             SetCommandExitStatus(true);
         }
 
-        switch (mTestIndex)
+        // Ensure we increment mTestIndex before we start running the relevant
+        // command.  That way if we lose the timeslice after we send the message
+        // but before our function call returns, we won't end up with an
+        // incorrect mTestIndex value observed when we get the response.
+        switch (mTestIndex++)
         {
         case 0:
             err = TestSendClusterOnOffCommandReadAttribute_0();
@@ -468,7 +475,6 @@ class OnOffCluster : public TestCommand
             err = TestSendClusterOnOffCommandReadAttribute_4();
             break;
         }
-        mTestIndex++;
 
         if (CHIP_NO_ERROR != err)
         {
@@ -480,8 +486,8 @@ class OnOffCluster : public TestCommand
     }
 
 private:
-    uint16_t mTestIndex = 0;
-    uint16_t mTestCount = 5;
+    std::atomic_uint16_t mTestIndex;
+    const uint16_t mTestCount = 5;
 
     //
     // Tests methods
diff --git a/examples/chip-tool/templates/partials/test_cluster.zapt b/examples/chip-tool/templates/partials/test_cluster.zapt
index 2a201787bb4525..5d461c438c043a 100644
--- a/examples/chip-tool/templates/partials/test_cluster.zapt
+++ b/examples/chip-tool/templates/partials/test_cluster.zapt
@@ -2,7 +2,7 @@
 class {{asCamelCased filename false}}: public TestCommand
 {
   public:
-    {{asCamelCased filename false}}(): TestCommand("{{filename}}") {}
+    {{asCamelCased filename false}}(): TestCommand("{{filename}}"), mTestIndex(0) {}
 
     /////////// TestCommand Interface /////////
     CHIP_ERROR NextTest() override
@@ -15,7 +15,11 @@ class {{asCamelCased filename false}}: public TestCommand
           SetCommandExitStatus(true);
       }
 
-      switch (mTestIndex)
+      // Ensure we increment mTestIndex before we start running the relevant
+      // command.  That way if we lose the timeslice after we send the message
+      // but before our function call returns, we won't end up with an
+      // incorrect mTestIndex value observed when we get the response.
+      switch (mTestIndex++)
       {
         {{#chip_tests_items}}
         case {{index}}:
@@ -23,7 +27,6 @@ class {{asCamelCased filename false}}: public TestCommand
           break;
         {{/chip_tests_items}}
       }
-      mTestIndex++;
 
       if (CHIP_NO_ERROR != err)
       {
@@ -36,8 +39,8 @@ class {{asCamelCased filename false}}: public TestCommand
 
 
   private:
-    uint16_t mTestIndex = 0;
-    uint16_t mTestCount = {{totalTests}};
+    std::atomic_uint16_t mTestIndex;
+    const uint16_t mTestCount = {{totalTests}};
 
     //
     // Tests methods