diff --git a/tools_webrtc/ios/client.webrtc.branches/iOS (beta).json b/tools_webrtc/ios/client.webrtc.branches/iOS (beta).json
index 8912312fd8..5ab132ede9 100644
--- a/tools_webrtc/ios/client.webrtc.branches/iOS (beta).json	
+++ b/tools_webrtc/ios/client.webrtc.branches/iOS (beta).json	
@@ -25,7 +25,7 @@
           "pool": "Chrome"
         },
         {
-          "os": "Mac-10.13",
+          "os": "Mac-10.13.3",
           "pool": "Chrome"
         }
       ]
diff --git a/tools_webrtc/ios/client.webrtc.branches/iOS (stable).json b/tools_webrtc/ios/client.webrtc.branches/iOS (stable).json
index 8912312fd8..5ab132ede9 100644
--- a/tools_webrtc/ios/client.webrtc.branches/iOS (stable).json	
+++ b/tools_webrtc/ios/client.webrtc.branches/iOS (stable).json	
@@ -25,7 +25,7 @@
           "pool": "Chrome"
         },
         {
-          "os": "Mac-10.13",
+          "os": "Mac-10.13.3",
           "pool": "Chrome"
         }
       ]
diff --git a/tools_webrtc/ios/client.webrtc/iOS64_Sim_Debug_(iOS_10.0).json b/tools_webrtc/ios/client.webrtc/iOS64_Sim_Debug_(iOS_10.0).json
index fe7558eaed..708f3ce48a 100644
--- a/tools_webrtc/ios/client.webrtc/iOS64_Sim_Debug_(iOS_10.0).json
+++ b/tools_webrtc/ios/client.webrtc/iOS64_Sim_Debug_(iOS_10.0).json
@@ -25,7 +25,7 @@
           "pool": "Chrome"
         },
         {
-          "os": "Mac-10.13",
+          "os": "Mac-10.13.3",
           "pool": "Chrome"
         }
       ]
diff --git a/tools_webrtc/ios/internal.client.webrtc/iOS64_Debug.json b/tools_webrtc/ios/internal.client.webrtc/iOS64_Debug.json
index 4a13c57c96..1531f86bb5 100644
--- a/tools_webrtc/ios/internal.client.webrtc/iOS64_Debug.json
+++ b/tools_webrtc/ios/internal.client.webrtc/iOS64_Debug.json
@@ -29,7 +29,7 @@
           "pool": "Chrome"
         },
         {
-          "os": "Mac-10.13",
+          "os": "Mac-10.13.3",
           "pool": "Chrome"
         }
       ]
diff --git a/tools_webrtc/ios/internal.client.webrtc/iOS64_Release.json b/tools_webrtc/ios/internal.client.webrtc/iOS64_Release.json
index e8c2d62861..8e5db4deef 100644
--- a/tools_webrtc/ios/internal.client.webrtc/iOS64_Release.json
+++ b/tools_webrtc/ios/internal.client.webrtc/iOS64_Release.json
@@ -30,7 +30,7 @@
           "pool": "Chrome"
         },
         {
-          "os": "Mac-10.13",
+          "os": "Mac-10.13.3",
           "pool": "Chrome"
         }
       ]
diff --git a/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_dbg.json b/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_dbg.json
index 4a13c57c96..1531f86bb5 100644
--- a/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_dbg.json
+++ b/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_dbg.json
@@ -29,7 +29,7 @@
           "pool": "Chrome"
         },
         {
-          "os": "Mac-10.13",
+          "os": "Mac-10.13.3",
           "pool": "Chrome"
         }
       ]
diff --git a/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_rel.json b/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_rel.json
index e8c2d62861..8e5db4deef 100644
--- a/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_rel.json
+++ b/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_rel.json
@@ -30,7 +30,7 @@
           "pool": "Chrome"
         },
         {
-          "os": "Mac-10.13",
+          "os": "Mac-10.13.3",
           "pool": "Chrome"
         }
       ]
diff --git a/tools_webrtc/ios/tryserver.webrtc/ios64_sim_ios10_dbg.json b/tools_webrtc/ios/tryserver.webrtc/ios64_sim_ios10_dbg.json
index 44a6063ca3..70c9976e60 100644
--- a/tools_webrtc/ios/tryserver.webrtc/ios64_sim_ios10_dbg.json
+++ b/tools_webrtc/ios/tryserver.webrtc/ios64_sim_ios10_dbg.json
@@ -26,7 +26,7 @@
           "pool": "Chrome"
         },
         {
-          "os": "Mac-10.13",
+          "os": "Mac-10.13.3",
           "pool": "Chrome"
         }
       ]