diff --git a/src/IO.cpp b/src/IO.cpp
index 69510f6dbf10003df6e6ebd677f46c2dd4ab9f8f..3c79b2278498822151fd7628bab0e0fbd883991f 100644
--- a/src/IO.cpp
+++ b/src/IO.cpp
@@ -110,7 +110,7 @@ std::variant<std::unordered_map<int, float>, std::string> IO::readHeightFile(con
 
                     if(auto inserted = markerHeights.insert(std::make_pair(markerID, height)); !inserted.second)
                     {
-                        return "Duplicate entry for markerID = " + std::to_string(markerID) + ".";
+                        return "File contains two height-entries for markerID = " + std::to_string(markerID) + ".";
                     }
                 }
                 else if(splitLine.empty())
diff --git a/tests/unit_test/tst_io.cpp b/tests/unit_test/tst_io.cpp
index bd5c4f29047b5ac65d35e76bab8cdeb4fa6cd9d2..97c7a97cbf3a0192e6c7c6cad0948c22f56b09ad 100644
--- a/tests/unit_test/tst_io.cpp
+++ b/tests/unit_test/tst_io.cpp
@@ -69,7 +69,8 @@ TEST_CASE("src/IO", "[tracking][io]")
                 auto errorMessage = IO::readHeightFile(QString::fromStdString(heigtFileName));
                 REQUIRE(std::holds_alternative<std::string>(errorMessage));
                 std::string errorAsString = std::get<std::string>(errorMessage);
-                REQUIRE_THAT(errorAsString, Catch::Matchers::Equals("Duplicate entry for markerID = 987."));
+                REQUIRE_THAT(
+                    errorAsString, Catch::Matchers::Equals("File contains two height-entries for markerID = 987."));
             }
 
             SECTION("Wrong inputs")