diff --git a/lib/clangimport.cpp b/lib/clangimport.cpp
index f4c66b738bc..60376ba7119 100644
--- a/lib/clangimport.cpp
+++ b/lib/clangimport.cpp
@@ -336,7 +336,10 @@ namespace clangimport {
     public:
         AstNode(std::string nodeType, const std::string &ext, Data *data)
             : nodeType(std::move(nodeType)), mExtTokens(splitString(ext)), mData(data)
-        {}
+        {
+            if (mExtTokens.empty())
+                throw InternalError(nullptr, "invalid AST node: " + this->nodeType, InternalError::AST);
+        }
         std::string nodeType;
         std::vector<AstNodePtr> children;
 
@@ -1408,7 +1411,10 @@ void clangimport::AstNode::createTokensFunctionDecl(TokenList &tokenList)
     auto *nestedIn = const_cast<Scope *>(nameToken->scope());
 
     if (prev) {
-        const std::string addr = *(std::find(mExtTokens.cbegin(), mExtTokens.cend(), "prev") + 1);
+        const auto it = std::find(mExtTokens.cbegin(), mExtTokens.cend(), "prev");
+        if (it + 1 == mExtTokens.cend())
+            throw InternalError(nullptr, "invalid AST node: " + nodeType, InternalError::AST);
+        const std::string addr = *(it + 1);
         mData->ref(addr, nameToken);
     }
     if (!nameToken->function()) {
@@ -1549,6 +1555,8 @@ void clangimport::AstNode::createTokensForCXXRecord(TokenList &tokenList)
 
 Token * clangimport::AstNode::createTokensVarDecl(TokenList &tokenList)
 {
+    if (mExtTokens.size() < 2)
+        throw InternalError(nullptr, "invalid AST node: " + nodeType, InternalError::AST);
     const std::string addr = mExtTokens.front();
     if (contains(mExtTokens, "static"))
         addtoken(tokenList, "static");
diff --git a/test/testclangimport.cpp b/test/testclangimport.cpp
index 13a27c7e7a0..865faa9a618 100644
--- a/test/testclangimport.cpp
+++ b/test/testclangimport.cpp
@@ -143,6 +143,7 @@ class TestClangImport : public TestFixture {
         TEST_CASE(crash);
         TEST_CASE(crash2);
         TEST_CASE(nullNodeInvalidLevel);
+        TEST_CASE(invalidExtTokens);
     }
 
     std::string parse(const char clang[]) {
@@ -1420,7 +1421,7 @@ class TestClangImport : public TestFixture {
         // getSpelling() indexed mExtTokens[typeIndex - 1] without a lower-bound
         // check, so a node whose line carries no ext tokens (typeIndex <= 0) read
         // out of bounds.
-        (void)parse("`-RecordDecl "); // don't crash
+        ASSERT_THROW_INTERNAL_EQUALS(parse("`-RecordDecl "), AST, "invalid AST node: RecordDecl");
     }
 
     void nullNodeInvalidLevel() {
@@ -1429,6 +1430,17 @@ class TestClangImport : public TestFixture {
                             "`-<<<NULL>>>\n";
         ASSERT_EQUALS("void foo ( ) ;", parse(clang));
     }
+
+    void invalidExtTokens() {
+        // nodes without the ext tokens the handlers read must not index out of bounds
+        ASSERT_THROW_INTERNAL_EQUALS(parse("`-FunctionDecl 0x1 <a.cpp:1:1, col:20> col:5 f 'int ()'\n"
+                                           "  `-CompoundStmt 0x2 <col:9, col:20>\n"
+                                           "    `-ReturnStmt 0x3 <col:11, col:18>\n"
+                                           "      `-IntegerLiteral \n"), AST, "invalid AST node: IntegerLiteral");
+        ASSERT_THROW_INTERNAL_EQUALS(parse("`-EnumDecl "), AST, "invalid AST node: EnumDecl");
+        ASSERT_THROW_INTERNAL_EQUALS(parse("`-VarDecl 0x1"), AST, "invalid AST node: VarDecl");
+        ASSERT_THROW_INTERNAL_EQUALS(parse("`-FunctionDecl 0x1 <a.cpp:1:1, col:20> col:5 f 'int ()' prev"), AST, "invalid AST node: FunctionDecl");
+    }
 };
 
 REGISTER_TEST(TestClangImport)