diff --git a/dashboard/builders.go b/dashboard/builders.go
index 733ff39..f794e2b 100644
--- a/dashboard/builders.go
+++ b/dashboard/builders.go
@@ -1821,6 +1821,7 @@
 		Name:              "darwin-amd64-10_11",
 		HostType:          "host-darwin-10_11",
 		tryBot:            nil, // disabled until Macs fixed; https://golang.org/issue/23859
+		buildsRepo:        onlyGo,
 		ShouldRunDistTest: noTestDir,
 		numTryTestHelpers: 3,
 	})
diff --git a/dashboard/builders_test.go b/dashboard/builders_test.go
index 45c8c6e..5d7ec5f 100644
--- a/dashboard/builders_test.go
+++ b/dashboard/builders_test.go
@@ -415,6 +415,14 @@
 		// Experimental exp repo.
 		{b("linux-amd64", "exp"), both},
 		{b("windows-386-2008", "exp"), both},
+
+		// Only use latest macOS for subrepos, and only amd64:
+		{b("darwin-amd64-10_12", "net"), onlyPost},
+		{b("darwin-amd64-10_12@go1.11", "net"), onlyPost},
+		{b("darwin-amd64-10_11", "net"), none},
+		{b("darwin-amd64-10_11@go1.11", "net"), none},
+		{b("darwin-amd64-10_11@go1.12", "net"), none},
+		{b("darwin-386-10_11@go1.11", "net"), none},
 	}
 	for _, tt := range tests {
 		t.Run(tt.br.testName, func(t *testing.T) {