diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index f9d6521b9..ee20203f0 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -5491,6 +5491,7 @@ void Tokenizer::simplifyIfAssign()
 
                 for (tok2 = tok2->next(); tok2 && tok2 != tok; tok2 = tok2->previous()) {
                     tok3->insertToken(tok2->str());
+                    tok3->next()->varId(tok2->varId());
 
                     Token *newTok = tok3->next();
                     newTok->fileIndex(tok2->fileIndex());
diff --git a/test/testsimplifytokens.cpp b/test/testsimplifytokens.cpp
index c6bcd068a..b564b0080 100644
--- a/test/testsimplifytokens.cpp
+++ b/test/testsimplifytokens.cpp
@@ -144,6 +144,7 @@ private:
         TEST_CASE(ifAssignWithCast);
         TEST_CASE(whileAssign1);
         TEST_CASE(whileAssign2);
+        TEST_CASE(whileAssign3); // varid
 
         // "if(0==x)" => "if(!x)"
         TEST_CASE(ifnot);
@@ -2507,6 +2508,19 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void whileAssign3() {
+        // #4254 - Variable id
+        const char code[] = "void f() {\n"
+                            "  int a;\n"
+                            "  while (a = x());\n"
+                            "}";
+        ASSERT_EQUALS("\n\n##file 0\n"
+                      "1: void f ( ) {\n"
+                      "2: int a@1 ;\n"
+                      "3: a@1 = x ( ) ; while ( a@1 ) { ; a@1 = x ( ) ; }\n"
+                      "4: }\n", tokenizeDebugListing(code, true, "test.c"));
+    }
+
 
     void ifnot() {
         ASSERT_EQUALS("if ( ! x ) { ; }", tok("if(0==x);", false));