diff --git a/lib/symboldatabase.cpp b/lib/symboldatabase.cpp
index a22f3bbf6..2be61124b 100644
--- a/lib/symboldatabase.cpp
+++ b/lib/symboldatabase.cpp
@@ -799,7 +799,7 @@ SymbolDatabase::SymbolDatabase(const Tokenizer *tokenizer, const Settings *setti
                     if (scope->definedType->needInitialization == Type::Unknown)
                         unknowns++;
                 }
-            } else if (scope->type == Scope::eUnion && scope->definedType->needInitialization == Type::Unknown)
+            } else if (scope->type == Scope::eUnion && scope->definedType && scope->definedType->needInitialization == Type::Unknown)
                 scope->definedType->needInitialization = Type::True;
         }
 
diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index 3a34efbcf..ca558ed46 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -8642,6 +8642,14 @@ void Tokenizer::simplifyKeyword()
         }
     }
 
+    if (_settings->standards.c >= Standards::C11) {
+        for (Token *tok = list.front(); tok; tok = tok->next()) {
+            while (tok->str() == "_Atomic") {
+                tok->deleteThis();
+            }
+        }
+    }
+
     if (_settings->standards.cpp >= Standards::CPP11) {
         for (Token *tok = list.front(); tok; tok = tok->next()) {
             while (Token::Match(tok, "constexpr|override")) {
diff --git a/test/testsymboldatabase.cpp b/test/testsymboldatabase.cpp
index af802e249..458b9e3fe 100644
--- a/test/testsymboldatabase.cpp
+++ b/test/testsymboldatabase.cpp
@@ -191,6 +191,7 @@ private:
         TEST_CASE(symboldatabase30);
         TEST_CASE(symboldatabase31);
         TEST_CASE(symboldatabase33); // ticket #4682 (false negatives)
+        TEST_CASE(symboldatabase34); // ticket #4694 (segmentation fault)
 
         TEST_CASE(isImplicitlyVirtual);
 
@@ -1496,6 +1497,15 @@ private:
         ASSERT(db && db->functionScopes.size() == 1);
     }
 
+    void symboldatabase34() { // ticket #4694
+        check("typedef _Atomic(int(A::*)) atomic_mem_ptr_to_int;\n"
+                      "typedef _Atomic(int)&atomic_int_ref;\n"
+                      "struct S {\n"
+                      "  _Atomic union { int n; };\n"
+                      "};");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void isImplicitlyVirtual() {
         {
             GET_SYMBOL_DB("class Base {\n"