diff --git a/Source/cmGeneratorExpressionEvaluationFile.cxx b/Source/cmGeneratorExpressionEvaluationFile.cxx
index e421c518fb..667b4e6cb1 100644
--- a/Source/cmGeneratorExpressionEvaluationFile.cxx
+++ b/Source/cmGeneratorExpressionEvaluationFile.cxx
@@ -54,17 +54,10 @@ void cmGeneratorExpressionEvaluationFile::Generate(
     }
   }
 
-  std::string outputFileName = this->OutputFileExpr->Evaluate(
-    lg, config, nullptr, nullptr, nullptr, lang);
+  const std::string outputFileName = this->GetOutputFileName(lg, config, lang);
   const std::string& outputContent =
     inputExpression->Evaluate(lg, config, nullptr, nullptr, nullptr, lang);
 
-  if (cmSystemTools::FileIsFullPath(outputFileName)) {
-    outputFileName = cmSystemTools::CollapseFullPath(outputFileName);
-  } else {
-    outputFileName = this->FixRelativePath(outputFileName, PathForOutput, lg);
-  }
-
   auto it = outputFiles.find(outputFileName);
 
   if (it != outputFiles.end()) {
@@ -183,6 +176,21 @@ std::string cmGeneratorExpressionEvaluationFile::GetInputFileName(
   return inputFileName;
 }
 
+std::string cmGeneratorExpressionEvaluationFile::GetOutputFileName(
+  cmLocalGenerator* lg, const std::string& config, const std::string& lang)
+{
+  std::string outputFileName = this->OutputFileExpr->Evaluate(
+    lg, config, nullptr, nullptr, nullptr, lang);
+
+  if (cmSystemTools::FileIsFullPath(outputFileName)) {
+    outputFileName = cmSystemTools::CollapseFullPath(outputFileName);
+  } else {
+    outputFileName = this->FixRelativePath(outputFileName, PathForOutput, lg);
+  }
+
+  return outputFileName;
+}
+
 std::string cmGeneratorExpressionEvaluationFile::FixRelativePath(
   std::string const& relativePath, PathRole role, cmLocalGenerator* lg)
 {
diff --git a/Source/cmGeneratorExpressionEvaluationFile.h b/Source/cmGeneratorExpressionEvaluationFile.h
index eb1e03d424..a258a2dbdf 100644
--- a/Source/cmGeneratorExpressionEvaluationFile.h
+++ b/Source/cmGeneratorExpressionEvaluationFile.h
@@ -39,6 +39,9 @@ private:
                 std::map<std::string, std::string>& outputFiles, mode_t perm);
 
   std::string GetInputFileName(cmLocalGenerator* lg);
+  std::string GetOutputFileName(cmLocalGenerator* lg,
+                                const std::string& config,
+                                const std::string& lang);
   enum PathRole
   {
     PathForInput,