diff --git a/src/ValueParsers/MonthNameUnlocalizer.php b/src/ValueParsers/MonthNameUnlocalizer.php
index ac90602..f44ae50 100644
--- a/src/ValueParsers/MonthNameUnlocalizer.php
+++ b/src/ValueParsers/MonthNameUnlocalizer.php
@@ -46,6 +46,10 @@ public function unlocalize( $date ) {
 			if ( !is_string( $search ) ) {
 				continue;
 			}
+			if ( !preg_match( '/\\p{L}/', $search ) ) {
+				// no letters in here (e.g. "1." for "jan"), do not use (might match day rather than month: T325988)
+				continue;
+			}
 
 			$unlocalized = str_replace( $search, $replace, $date, $count );
 
diff --git a/tests/ValueParsers/MonthNameUnlocalizerTest.php b/tests/ValueParsers/MonthNameUnlocalizerTest.php
index d7baa17..7a98288 100644
--- a/tests/ValueParsers/MonthNameUnlocalizerTest.php
+++ b/tests/ValueParsers/MonthNameUnlocalizerTest.php
@@ -79,6 +79,10 @@ public function localizedDateProvider() {
 			array( '2000', '2000', array(
 				'2' => 'February',
 			) ),
+			// And others (e.g. cs) just repeat the number of the month with punctuation
+			array( '5. 4. 1891', '5. 4. 1891', array(
+				'5.' => 'May',
+			) ),
 		);
 	}