diff --git a/lib/symboldatabase.cpp b/lib/symboldatabase.cpp
index 375330487..34c02870a 100644
--- a/lib/symboldatabase.cpp
+++ b/lib/symboldatabase.cpp
@@ -24,6 +24,7 @@
 #include "settings.h"
 #include "errorlogger.h"
 #include "check.h"
+#include "checknullpointer.h"  // isUpper
 
 #include <string>
 #include <sstream>
@@ -95,6 +96,34 @@ SymbolDatabase::SymbolDatabase(const Tokenizer *tokenizer, const Settings *setti
             tok = tok2;
         }
 
+        // Namespace and unknown macro (#3854)
+        else if (Token::Match(tok, "namespace %var% %type% (") &&
+                 _tokenizer->isCPP() &&
+                 CheckNullPointer::isUpper(tok->strAt(2)) &&
+                 Token::simpleMatch(tok->linkAt(3), ") {")) {
+            scopeList.push_back(Scope(this, tok, scope));
+
+            Scope *new_scope = &scopeList.back();
+            access[new_scope] = Public;
+
+            const Token *tok2 = tok->linkAt(3)->next();
+
+            new_scope->classStart = tok2;
+            new_scope->classEnd = tok2->link();
+
+            // make sure we have valid code
+            if (!new_scope->classEnd) {
+                scopeList.pop_back();
+                break;
+            }
+
+            // make the new scope the current scope
+            scope = &scopeList.back();
+            scope->nestedIn->nestedList.push_back(scope);
+
+            tok = tok2;
+        }
+
         // forward declaration
         else if (Token::Match(tok, "class|struct %var% ;")) {
             // fill the classAndStructTypes set..
diff --git a/test/testsymboldatabase.cpp b/test/testsymboldatabase.cpp
index 1c0eca125..5d8da391d 100644
--- a/test/testsymboldatabase.cpp
+++ b/test/testsymboldatabase.cpp
@@ -114,6 +114,7 @@ private:
 
         TEST_CASE(namespaces1);
         TEST_CASE(namespaces2);
+        TEST_CASE(namespaces3);  // #3854 - unknown macro
 
         TEST_CASE(tryCatch1);
 
@@ -865,6 +866,13 @@ private:
         ASSERT_EQUALS(true, function->hasBody);
     }
 
+    void namespaces3() {	// #3854 - namespace with unknown macro
+        GET_SYMBOL_DB("namespace fred UNKNOWN_MACRO(default) {\n"
+                      "}\n");
+        ASSERT_EQUALS(2U, db->scopeList.size());
+        ASSERT_EQUALS(Scope::eGlobal, db->scopeList.front().type);
+        ASSERT_EQUALS(Scope::eNamespace, db->scopeList.back().type);
+    }
 
     void tryCatch1() {
         const std::string str("void foo() {\n"