diff --git a/src/main/kotlin/nl/lengrand/opengraphkt/Parser.kt b/src/main/kotlin/nl/lengrand/opengraphkt/Parser.kt
index 3f6d3b6..4fc88c0 100644
--- a/src/main/kotlin/nl/lengrand/opengraphkt/Parser.kt
+++ b/src/main/kotlin/nl/lengrand/opengraphkt/Parser.kt
@@ -50,11 +50,18 @@ class Parser {
         println(tags)
         println(cleanTags)
 
-        // Extract the basic required Open Graph properties
-        val title = tags.select("meta[property=og:title]").attr("content")
-        val image = tags.select("meta[property=og:image]").attr("content")
-        val url = tags.select("meta[property=og:url]").attr("content")
-        val type = tags.select("meta[property=og:type]").attr("content")
+        val title =
+            if (tags.select("meta[property=og:title]").isEmpty()) null
+            else tags.select("meta[property=og:title]").attr("content")
+        val image =
+            if (tags.select("meta[property=og:image]").isEmpty()) null
+            else tags.select("meta[property=og:image]").attr("content")
+        val url =
+            if (tags.select("meta[property=og:url]").isEmpty()) null
+            else tags.select("meta[property=og:url]").attr("content")
+        val type =
+            if (tags.select("meta[property=og:type]").isEmpty()) null
+            else tags.select("meta[property=og:type]").attr("content")
 
         return OpenGraph(
             tags,
diff --git a/src/test/kotlin/nl/lengrand/opengraphkt/ParserTest.kt b/src/test/kotlin/nl/lengrand/opengraphkt/ParserTest.kt
index 07efa72..162a186 100644
--- a/src/test/kotlin/nl/lengrand/opengraphkt/ParserTest.kt
+++ b/src/test/kotlin/nl/lengrand/opengraphkt/ParserTest.kt
@@ -92,21 +92,15 @@ class ParserTest {
         val document = fetcher.fromString(incompleteHtml)
         val openGraph = parser.extractOpenGraphTags(document)
 
-        // Verify that the available property is extracted correctly
         assertEquals("The Rock", openGraph.title)
 
-        // Verify that missing properties are empty strings
-        assertEquals("", openGraph.type)
-        assertEquals("", openGraph.url)
-        assertEquals("", openGraph.image)
+        assertEquals(null, openGraph.type)
+        assertEquals(null, openGraph.url)
+        assertEquals(null, openGraph.image)
 
-        // Verify that the OpenGraph object is not valid due to missing required properties
         assertFalse(openGraph.isValid())
-
-        // Verify that only the available tags are extracted
         assertEquals(2, openGraph.tags.size)
 
-        // Verify specific tag content
         val descriptionTag = openGraph.tags.find { it.property == "description" }
         assertNotNull(descriptionTag)
         assertEquals("An action movie about a rock", descriptionTag.content)
@@ -117,16 +111,13 @@ class ParserTest {
         val document = fetcher.fromString(noOgHtml)
         val openGraph = parser.extractOpenGraphTags(document)
 
-        // Verify that all properties are empty strings
-        assertEquals("", openGraph.title)
-        assertEquals("", openGraph.type)
-        assertEquals("", openGraph.url)
-        assertEquals("", openGraph.image)
+        // Verify that all properties are null
+        assertEquals(null, openGraph.title)
+        assertEquals(null, openGraph.type)
+        assertEquals(null, openGraph.url)
+        assertEquals(null, openGraph.image)
 
-        // Verify that the OpenGraph object is not valid
         assertFalse(openGraph.isValid())
-
-        // Verify that no tags are extracted
         assertEquals(0, openGraph.tags.size)
     }
 }