diff --git a/libcextract/ClangCompat.hh b/libcextract/ClangCompat.hh
index 07571ac..df86b7d 100644
--- a/libcextract/ClangCompat.hh
+++ b/libcextract/ClangCompat.hh
@@ -36,6 +36,14 @@
 #include <clang/Basic/Version.h>
 #include "clang/Frontend/CompilerInstance.h"
 
+/* Starting from LLVM-18, the method FileEntry::getName() got deprecated.
+ * This makes clang warns about the function being deprecated while it is
+ * completely useful as a way to keep compatibility with older versions of
+ * LLVM, hence we acknowledge the warning here and disable it for now.
+ */
+
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+
 namespace ClangCompat
 {
 #if CLANG_VERSION_MAJOR >= 16
diff --git a/libcextract/IncludeTree.cpp b/libcextract/IncludeTree.cpp
index 36ad22c..acb4dce 100644
--- a/libcextract/IncludeTree.cpp
+++ b/libcextract/IncludeTree.cpp
@@ -123,6 +123,16 @@ void IncludeTree::Build_Header_Tree(std::vector<std::string> const &must_expand)
       bool expand = In_Set(must_expand_set, id->getFileName().str(), /*remove=*/true) ||
                     In_Set(must_expand_set, id->getFile()->getName().str(),
                            /*remove=*/true);
+#if CLANG_VERSION_MAJOR >= 18
+      /* Starting from LLVM-18, the behaviour of FileEntry::getName() changed.
+       * Now it returns the full path of the file rather than the relative path
+       * to it, so here we account it for now onwards.
+       */
+      expand |= In_Set(must_expand_set,
+                       id->getFile()->getFileEntry().tryGetRealPathName().str(),
+                       /*remove=*/true);
+#endif
+
       bool output = already_seen_main && current->Should_Be_Expanded()
                                       && !expand;
       bool is_from_minus_include = !already_seen_main;
@@ -355,11 +365,10 @@ void IncludeTree::IncludeNode::Set_FileEntry(OptionalFileEntryRef file)
 
 SourceRange IncludeTree::IncludeNode::Get_File_Range(void)
 {
-  const FileEntry *file = *File;
   SourceManager *SM = PrettyPrint::Get_Source_Manager();
 
   SourceLocation start, end;
-  FileID fid = SM->getOrCreateFileID(file, SrcMgr::CharacteristicKind());
+  FileID fid = SM->getOrCreateFileID(*File, SrcMgr::CharacteristicKind());
   start = SM->getLocForStartOfFile(fid);
   end = SM->getLocForEndOfFile(fid);
 
diff --git a/libcextract/Passes.cpp b/libcextract/Passes.cpp
index bd5a562..ca6ffa9 100644
--- a/libcextract/Passes.cpp
+++ b/libcextract/Passes.cpp
@@ -188,7 +188,12 @@ class BuildASTPass : public Pass
   {
     SourceManager &sm = ast->getSourceManager();
 
+#if CLANG_VERSION_MAJOR >= 18
+    FileEntryRef main_file = *sm.getFileEntryRefForID(sm.getMainFileID());
+#else
     const FileEntry *main_file = sm.getFileEntryForID(sm.getMainFileID());
+#endif
+
     StringRef path = sm.getFileManager().getCanonicalName(main_file);
 
     return path;
diff --git a/libcextract/SymbolExternalizer.cpp b/libcextract/SymbolExternalizer.cpp
index d8b4eae..1692c82 100644
--- a/libcextract/SymbolExternalizer.cpp
+++ b/libcextract/SymbolExternalizer.cpp
@@ -16,6 +16,7 @@
 #include "SymbolExternalizer.hh"
 #include "PrettyPrint.hh"
 #include "Error.hh"
+#include "ClangCompat.hh"
 
 #include <unordered_set>
 #include <iostream>
@@ -365,7 +366,6 @@ bool TextModifications::Is_Same_Change(const Delta &a, const Delta &b)
 
 /* ---- End of Deltas class -------- */
 
-
 bool SymbolExternalizer::FunctionUpdater::Update_References_To_Symbol(Stmt *stmt)
 {
   if (!stmt)
diff --git a/testsuite/includes/include-7.c b/testsuite/includes/include-7.c
index 96615e2..0d6f927 100644
--- a/testsuite/includes/include-7.c
+++ b/testsuite/includes/include-7.c
@@ -9,7 +9,6 @@ int main(void)
 }
 
 /* { dg-final { scan-tree-dump "#define _STDIO_H	1" } } */
-/* { dg-final { scan-tree-dump "typedef __SIZE_TYPE__ size_t;" } } */
 /* { dg-final { scan-tree-dump "#define __need___va_list" } } */
 /* { dg-final { scan-tree-dump "#include <stdarg.h>" } } */
 /* { dg-final { scan-tree-dump "#include <bits/types/__fpos_t.h>" } } */