diff --git a/meta/lib/oe/sbom30.py b/meta/lib/oe/sbom30.py
index e02382c3cc78..5af2e4ff1c0c 100644
--- a/meta/lib/oe/sbom30.py
+++ b/meta/lib/oe/sbom30.py
@@ -397,7 +397,11 @@ class ObjectSet(oe.spdx30.SHACLObjectSet):
         self.doc.import_.append(m)
         return spdxid
 
-    def new_agent(self, varname, *, creation_info=None, add=True):
+    def new_agent(self, varname, *, creation_info=None, add=True, expand=False):
+        if expand:
+            varname = self.d.getVar(f"{varname}")
+            if not varname:
+                return None
         ref_varname = self.d.getVar(f"{varname}_ref")
         if ref_varname:
             if ref_varname == varname:
diff --git a/meta/lib/oe/spdx30_tasks.py b/meta/lib/oe/spdx30_tasks.py
index dac02e378429..88c707476a65 100644
--- a/meta/lib/oe/spdx30_tasks.py
+++ b/meta/lib/oe/spdx30_tasks.py
@@ -905,7 +905,7 @@ def create_spdx(d):
                 force_purposes=["install"],
             )
 
-            supplier = build_objset.new_agent("SPDX_PACKAGE_SUPPLIER")
+            supplier = build_objset.new_agent("SPDX_PACKAGE_SUPPLIER", expand=True)
             if supplier is not None:
                 spdx_package.suppliedBy = (
                     supplier if isinstance(supplier, str) else supplier._id
@@ -1213,8 +1213,8 @@ def write_bitbake_spdx(d):
     objset = oe.sbom30.ObjectSet.new_objset(d, "bitbake", False)
 
     host_import_key = d.getVar("SPDX_BUILD_HOST")
-    invoked_by = objset.new_agent("SPDX_INVOKED_BY", add=False)
-    on_behalf_of = objset.new_agent("SPDX_ON_BEHALF_OF", add=False)
+    invoked_by = objset.new_agent("SPDX_INVOKED_BY", add=False, expand=True)
+    on_behalf_of = objset.new_agent("SPDX_ON_BEHALF_OF", add=False, expand=True)
 
     if d.getVar("SPDX_INCLUDE_BITBAKE_PARENT_BUILD") == "1":
         # Since the Build objects are unique, we may as well set the creation
@@ -1536,7 +1536,7 @@ def create_image_sbom_spdx(d):
     objset, sbom = oe.sbom30.create_sbom(d, image_name, root_elements)
 
     # Set supplier on root elements if SPDX_IMAGE_SUPPLIER is defined
-    supplier = objset.new_agent("SPDX_IMAGE_SUPPLIER", add=False)
+    supplier = objset.new_agent("SPDX_IMAGE_SUPPLIER", add=False, expand=True)
     if supplier is not None:
         supplier_id = supplier if isinstance(supplier, str) else supplier._id
         if not isinstance(supplier, str):
@@ -1657,7 +1657,7 @@ def create_sdk_sbom(d, sdk_deploydir, spdx_work_dir, toolchain_outputname):
     )
 
     # Set supplier on root elements if SPDX_SDK_SUPPLIER is defined
-    supplier = objset.new_agent("SPDX_SDK_SUPPLIER", add=False)
+    supplier = objset.new_agent("SPDX_SDK_SUPPLIER", add=False, expand=True)
     if supplier is not None:
         supplier_id = supplier if isinstance(supplier, str) else supplier._id
         if not isinstance(supplier, str):