diff --git a/meta/classes-recipe/populate_sdk_base.bbclass b/meta/classes-recipe/populate_sdk_base.bbclass
index 6cb43ad..a103e7b 100644
--- a/meta/classes-recipe/populate_sdk_base.bbclass
+++ b/meta/classes-recipe/populate_sdk_base.bbclass
@@ -4,6 +4,9 @@
 # SPDX-License-Identifier: MIT
 #
 
+SDK_CLASSES += "${@bb.utils.contains("IMAGE_CLASSES", "testimage", "testsdk", "", d)}"
+inherit_defer ${SDK_CLASSES}
+
 PACKAGES = ""
 
 # This exists as an optimization for SPDX processing to only run in image and
diff --git a/meta/classes-recipe/testimage.bbclass b/meta/classes-recipe/testimage.bbclass
index ed0d87b..2f68f83 100644
--- a/meta/classes-recipe/testimage.bbclass
+++ b/meta/classes-recipe/testimage.bbclass
@@ -483,5 +483,3 @@ python () {
     if oe.types.boolean(d.getVar("TESTIMAGE_AUTO") or "False"):
         bb.build.addtask("testimage", "do_build", "do_image_complete", d)
 }
-
-inherit testsdk
diff --git a/meta/recipes-core/meta/buildtools-tarball.bb b/meta/recipes-core/meta/buildtools-tarball.bb
index 92fbda3..e2ce5b3 100644
--- a/meta/recipes-core/meta/buildtools-tarball.bb
+++ b/meta/recipes-core/meta/buildtools-tarball.bb
@@ -112,6 +112,9 @@ INHIBIT_DEFAULT_DEPS = "1"
 # Directory in testsdk that contains testcases
 TESTSDK_CASES = "buildtools-cases"
 
+# We have our own code, avoid deferred inherit
+SDK_CLASSES:remove = "testsdk"
+
 python do_testsdk() {
     import oeqa.sdk.testsdk
     testsdk = oeqa.sdk.testsdk.TestSDK()