diff --git a/src/NodaTimeSplitter.php b/src/NodaTimeSplitter.php
index dfdae6c..d5c3129 100644
--- a/src/NodaTimeSplitter.php
+++ b/src/NodaTimeSplitter.php
@@ -797,13 +797,13 @@ final class NodaTimeSplitter {
         $datum = self::clean_input($datum);
         $bcBceIndicator = '+';
 
-        if (preg_match("/^[0-9]0(er\ Jahre|\-es\ évek|\-as\ \évek)$/", $datum)) {
+        if (preg_match("/^[0-9]0(er|er\ Jahre|\-es\ évek|\-as\ \évek)$/", $datum)) {
             $start = "19" . substr($datum, 0, 2);
             $ende = (string)(intval($start) + 9);
             return [$start, $ende, "00", "00", $bcBceIndicator, ""];
         }
 
-        if (preg_match("/^[0-9][0-9][0-9]0(er\ Jahre|\-es\ évek|\-as\ \évek)$/", $datum)) {
+        if (preg_match("/^[0-9][0-9][0-9]0(er|er\ Jahre|\-es\ évek|\-as\ \évek)$/", $datum)) {
             $start = substr($datum, 0, 4);
             $ende = (string)(intval($start) + 9);
             return [$start, $ende, "00", "00", $bcBceIndicator, ""];
diff --git a/tests/NodaTimeSplitterTest.php b/tests/NodaTimeSplitterTest.php
index c0e4490..f597549 100644
--- a/tests/NodaTimeSplitterTest.php
+++ b/tests/NodaTimeSplitterTest.php
@@ -120,6 +120,18 @@ final class NodaTimeSplitterTest extends TestCase {
         self::assertEquals(NodaTimeSplitter::timePartsToTimeName($output), "1920-1929");
         self::assertEquals(NodaTimeSplitter::timePartsToCountingYear($output), 1925);
 
+        $output = NodaTimeSplitter::attempt_splitting("20er");
+        self::assertEquals($output, [
+            0 => "1920",
+            1 => "1929",
+            2 => "00",
+            3 => "00",
+            4 => "+",
+            5 => "",
+        ]);
+        self::assertEquals(NodaTimeSplitter::timePartsToTimeName($output), "1920-1929");
+        self::assertEquals(NodaTimeSplitter::timePartsToCountingYear($output), 1925);
+
         $output = NodaTimeSplitter::attempt_splitting("1920er Jahre");
         self::assertEquals($output, [
             0 => "1920",