diff --git a/core/dictgen/src/rootcling_impl.cxx b/core/dictgen/src/rootcling_impl.cxx
index 2df77178d3093..57a229446dd7c 100644
--- a/core/dictgen/src/rootcling_impl.cxx
+++ b/core/dictgen/src/rootcling_impl.cxx
@@ -3345,11 +3345,12 @@ class TRootClingCallbacks : public cling::InterpreterCallbacks {
       if (!curLexer) return;
       auto fileEntry = curLexer->getFileEntry();
       if (!fileEntry) return;
-      auto thisFileName = fileEntry->getName();
+      auto thisFileName = llvm::sys::path::filename(fileEntry->getName()).str();
       auto fileNameAsString = FileName.str();
-      auto isThisLinkdef = ROOT::TMetaUtils::IsLinkdefFile(thisFileName.data());
+      auto isThisLinkdef = ROOT::TMetaUtils::IsLinkdefFile(thisFileName.c_str());
       if (isThisLinkdef) {
-         auto isTheIncludedLinkdef = ROOT::TMetaUtils::IsLinkdefFile(fileNameAsString.c_str());
+         auto includedFileName = llvm::sys::path::filename(FileName).str();
+         auto isTheIncludedLinkdef = ROOT::TMetaUtils::IsLinkdefFile(includedFileName.c_str());
          if (isTheIncludedLinkdef) {
             fFilesIncludedByLinkdef.clear();
             isLocked = true;
diff --git a/roottest/root/meta/rootcling/CMakeLists.txt b/roottest/root/meta/rootcling/CMakeLists.txt
index a915789400f99..9aacc7abef034 100644
--- a/roottest/root/meta/rootcling/CMakeLists.txt
+++ b/roottest/root/meta/rootcling/CMakeLists.txt
@@ -30,6 +30,36 @@ ROOTTEST_ADD_TEST(includeInLinkdef
                   COPY_TO_BUILDDIR headerForLdef.h
                   FIXTURES_REQUIRED root-meta-roocling-includeInLinkdefDict-fixture)
 
+# Directory names must not make ordinary headers look like LinkDef files.
+ROOTTEST_GENERATE_DICTIONARY(includeDirectoryDict
+                             includeDirectory.h
+                             LINKDEF includeDirectoryLinkDef.h
+                             FIXTURES_SETUP root-meta-rootcling-includeDirectoryDict-fixture)
+
+ROOTTEST_ADD_TEST(includeDirectory
+                  MACRO assertIncludeDictionary.C
+                  MACROARG "\"includeDirectoryDict\",\"RootclingDirectory::Payload\""
+                  FIXTURES_REQUIRED root-meta-rootcling-includeDirectoryDict-fixture)
+
+ROOTTEST_GENERATE_DICTIONARY(includeDirectoryFromSelectionDict
+                             LINKDEF includeDirectoryFromSelectionLinkDef.h
+                             FIXTURES_SETUP root-meta-rootcling-includeDirectoryFromSelectionDict-fixture)
+
+ROOTTEST_ADD_TEST(includeDirectoryFromSelection
+                  MACRO assertIncludeDictionary.C
+                  MACROARG "\"includeDirectoryFromSelectionDict\",\"RootclingDirectory::DirectPayload\""
+                  FIXTURES_REQUIRED root-meta-rootcling-includeDirectoryFromSelectionDict-fixture)
+
+ROOTTEST_GENERATE_DICTIONARY(includeNestedDict
+                             includeNested.h
+                             LINKDEF NestedSelection/OuterLinkDef.h
+                             FIXTURES_SETUP root-meta-rootcling-includeNestedDict-fixture)
+
+ROOTTEST_ADD_TEST(includeNested
+                  MACRO assertIncludeDictionary.C
+                  MACROARG "\"includeNestedDict\",\"RootclingNested::Payload\""
+                  FIXTURES_REQUIRED root-meta-rootcling-includeNestedDict-fixture)
+
 # ROOT-8492
 ROOTTEST_ADD_TEST(selectUnion
                   COMMAND ${ROOT_rootcling_CMD} -f NestedClassOff.Dict.cc ${CMAKE_CURRENT_SOURCE_DIR}/NestedClassOff.h ${CMAKE_CURRENT_SOURCE_DIR}/NestedClassOff.LinkDef.h
diff --git a/roottest/root/meta/rootcling/LinkDefDirectory/Wrapper.h b/roottest/root/meta/rootcling/LinkDefDirectory/Wrapper.h
new file mode 100644
index 0000000000000..a58cb8c81ebb8
--- /dev/null
+++ b/roottest/root/meta/rootcling/LinkDefDirectory/Wrapper.h
@@ -0,0 +1,6 @@
+#ifndef ROOTTEST_ROOT_META_ROOTCLING_DIRECTORY_WRAPPER_H
+#define ROOTTEST_ROOT_META_ROOTCLING_DIRECTORY_WRAPPER_H
+
+#include "detail/Payload.h"
+
+#endif
diff --git a/roottest/root/meta/rootcling/LinkDefDirectory/detail/Payload.h b/roottest/root/meta/rootcling/LinkDefDirectory/detail/Payload.h
new file mode 100644
index 0000000000000..81d338110f4de
--- /dev/null
+++ b/roottest/root/meta/rootcling/LinkDefDirectory/detail/Payload.h
@@ -0,0 +1,13 @@
+#ifndef ROOTTEST_ROOT_META_ROOTCLING_DIRECTORY_PAYLOAD_H
+#define ROOTTEST_ROOT_META_ROOTCLING_DIRECTORY_PAYLOAD_H
+
+namespace RootclingDirectory {
+struct Payload {
+   int value = 0;
+};
+struct DirectPayload {
+   int value = 0;
+};
+} // namespace RootclingDirectory
+
+#endif
diff --git a/roottest/root/meta/rootcling/NestedSelection/After.h b/roottest/root/meta/rootcling/NestedSelection/After.h
new file mode 100644
index 0000000000000..4cfb545bfd9a7
--- /dev/null
+++ b/roottest/root/meta/rootcling/NestedSelection/After.h
@@ -0,0 +1,5 @@
+// Parsing this selection-only header in rootcling is intentional. The guard
+// detects an unwanted direct include during later dictionary C++ compilation.
+#ifndef __ROOTCLING__
+#error "Headers collected after a nested LinkDef must not be emitted directly."
+#endif
diff --git a/roottest/root/meta/rootcling/NestedSelection/Before.h b/roottest/root/meta/rootcling/NestedSelection/Before.h
new file mode 100644
index 0000000000000..bf86672086878
--- /dev/null
+++ b/roottest/root/meta/rootcling/NestedSelection/Before.h
@@ -0,0 +1,5 @@
+// Parsing this selection-only header in rootcling is intentional. The guard
+// detects an unwanted direct include during later dictionary C++ compilation.
+#ifndef __ROOTCLING__
+#error "Headers collected before a nested LinkDef must not be emitted directly."
+#endif
diff --git a/roottest/root/meta/rootcling/NestedSelection/InnerLinkDef.h b/roottest/root/meta/rootcling/NestedSelection/InnerLinkDef.h
new file mode 100644
index 0000000000000..2062fc78f3591
--- /dev/null
+++ b/roottest/root/meta/rootcling/NestedSelection/InnerLinkDef.h
@@ -0,0 +1,6 @@
+#ifdef __ROOTCLING__
+#pragma link off all globals;
+#pragma link off all classes;
+#pragma link off all functions;
+#pragma link C++ class RootclingNested::Payload + ;
+#endif
diff --git a/roottest/root/meta/rootcling/NestedSelection/OuterLinkDef.h b/roottest/root/meta/rootcling/NestedSelection/OuterLinkDef.h
new file mode 100644
index 0000000000000..5890bda2539c8
--- /dev/null
+++ b/roottest/root/meta/rootcling/NestedSelection/OuterLinkDef.h
@@ -0,0 +1,3 @@
+#include "Before.h"
+#include "InnerLinkDef.h"
+#include "After.h"
diff --git a/roottest/root/meta/rootcling/NestedSelection/Payload.h b/roottest/root/meta/rootcling/NestedSelection/Payload.h
new file mode 100644
index 0000000000000..ccf141a6a6213
--- /dev/null
+++ b/roottest/root/meta/rootcling/NestedSelection/Payload.h
@@ -0,0 +1,10 @@
+#ifndef ROOTTEST_ROOT_META_ROOTCLING_NESTED_PAYLOAD_H
+#define ROOTTEST_ROOT_META_ROOTCLING_NESTED_PAYLOAD_H
+
+namespace RootclingNested {
+struct Payload {
+   int value = 0;
+};
+} // namespace RootclingNested
+
+#endif
diff --git a/roottest/root/meta/rootcling/assertIncludeDictionary.C b/roottest/root/meta/rootcling/assertIncludeDictionary.C
new file mode 100644
index 0000000000000..20e52ad19ff53
--- /dev/null
+++ b/roottest/root/meta/rootcling/assertIncludeDictionary.C
@@ -0,0 +1,34 @@
+#include "TClass.h"
+#include "TClassTable.h"
+#include "TError.h"
+#include "TSystem.h"
+
+#include <cstring>
+
+int assertIncludeDictionary(const char *library, const char *className)
+{
+   // Each CTest invocation starts a fresh ROOT process. Do not let a dictionary
+   // loaded by another case hide a missing selection in the requested library.
+   if (TClassTable::GetDictNorm(className)) {
+      Error("assertIncludeDictionary", "Dictionary for %s was already registered", className);
+      return 1;
+   }
+   if (gSystem->Load(library) < 0) {
+      Error("assertIncludeDictionary", "Could not load %s", library);
+      return 2;
+   }
+
+   // Look up the compiled registration directly, without interpreter fallback,
+   // header autoparsing or autoloading a different dictionary library.
+   auto dictionary = TClassTable::GetDictNorm(className);
+   if (!dictionary) {
+      Error("assertIncludeDictionary", "%s did not register a dictionary for %s", library, className);
+      return 3;
+   }
+   auto cl = dictionary();
+   if (!cl || !cl->HasDictionary() || std::strcmp(cl->GetName(), className) != 0) {
+      Error("assertIncludeDictionary", "Invalid compiled dictionary for %s from %s", className, library);
+      return 4;
+   }
+   return 0;
+}
diff --git a/roottest/root/meta/rootcling/includeDirectory.h b/roottest/root/meta/rootcling/includeDirectory.h
new file mode 100644
index 0000000000000..75d646b744524
--- /dev/null
+++ b/roottest/root/meta/rootcling/includeDirectory.h
@@ -0,0 +1 @@
+#include "LinkDefDirectory/Wrapper.h"
diff --git a/roottest/root/meta/rootcling/includeDirectoryFromSelectionLinkDef.h b/roottest/root/meta/rootcling/includeDirectoryFromSelectionLinkDef.h
new file mode 100644
index 0000000000000..8beee46f9e18d
--- /dev/null
+++ b/roottest/root/meta/rootcling/includeDirectoryFromSelectionLinkDef.h
@@ -0,0 +1,8 @@
+#include "LinkDefDirectory/Wrapper.h"
+
+#ifdef __ROOTCLING__
+#pragma link off all globals;
+#pragma link off all classes;
+#pragma link off all functions;
+#pragma link C++ class RootclingDirectory::DirectPayload + ;
+#endif
diff --git a/roottest/root/meta/rootcling/includeDirectoryLinkDef.h b/roottest/root/meta/rootcling/includeDirectoryLinkDef.h
new file mode 100644
index 0000000000000..ca6a7f8a5f8f2
--- /dev/null
+++ b/roottest/root/meta/rootcling/includeDirectoryLinkDef.h
@@ -0,0 +1,6 @@
+#ifdef __ROOTCLING__
+#pragma link off all globals;
+#pragma link off all classes;
+#pragma link off all functions;
+#pragma link C++ class RootclingDirectory::Payload + ;
+#endif
diff --git a/roottest/root/meta/rootcling/includeNested.h b/roottest/root/meta/rootcling/includeNested.h
new file mode 100644
index 0000000000000..531916d84b50b
--- /dev/null
+++ b/roottest/root/meta/rootcling/includeNested.h
@@ -0,0 +1 @@
+#include "NestedSelection/Payload.h"