diff --git a/src/main/java/net/sf/jabref/importer/fileformat/MedlinePlainImporter.java b/src/main/java/net/sf/jabref/importer/fileformat/MedlinePlainImporter.java
index 2d8881d2fb2..b3a03ccda0a 100644
--- a/src/main/java/net/sf/jabref/importer/fileformat/MedlinePlainImporter.java
+++ b/src/main/java/net/sf/jabref/importer/fileformat/MedlinePlainImporter.java
@@ -127,6 +127,9 @@ public ParserResult importDatabase(BufferedReader reader) throws IOException {
                     }
                 }
                 String entry = current.toString();
+                if (!checkLineValidity(entry)) {
+                    continue;
+                }
 
                 String label = entry.substring(0, entry.indexOf('-')).trim();
                 String value = entry.substring(entry.indexOf('-') + 1).trim();
@@ -227,13 +230,16 @@ public ParserResult importDatabase(BufferedReader reader) throws IOException {
             // create one here
             b.setField(fields);
             bibitems.add(b);
-
         }
 
         return new ParserResult(bibitems);
 
     }
 
+    private boolean checkLineValidity(String line) {
+        return (line.length() >= 5) && (line.charAt(4) == '-');
+    }
+
     private String addSourceType(String value, String type) {
         String val = value.toLowerCase(Locale.ENGLISH);
         String theType = type;
diff --git a/src/test/java/net/sf/jabref/importer/fileformat/MedlinePlainImporterTest.java b/src/test/java/net/sf/jabref/importer/fileformat/MedlinePlainImporterTest.java
index 8c7aed816e9..42ccccf4866 100644
--- a/src/test/java/net/sf/jabref/importer/fileformat/MedlinePlainImporterTest.java
+++ b/src/test/java/net/sf/jabref/importer/fileformat/MedlinePlainImporterTest.java
@@ -19,11 +19,13 @@
 import net.sf.jabref.model.entry.BibEntry;
 import net.sf.jabref.preferences.JabRefPreferences;
 
+import org.apache.commons.codec.Charsets;
 import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
 
 public class MedlinePlainImporterTest {
 
@@ -197,6 +199,30 @@ public void testWithNbibFile() throws IOException, URISyntaxException {
         BibEntryAssert.assertEquals(MedlinePlainImporter.class, "NbibImporterTest.bib", entries);
     }
 
+    @Test
+    public void testWithMultipleEntries() throws IOException, URISyntaxException {
+        Path file = Paths
+                .get(MedlinePlainImporter.class.getResource("MedlinePlainImporterStringOutOfBounds.txt").toURI());
+        List<BibEntry> entries = importer.importDatabase(file, Charsets.UTF_8).getDatabase().getEntries();
+        BibEntryAssert.assertEquals(MedlinePlainImporter.class, "MedlinePlainImporterStringOutOfBounds.bib", entries);
+    }
+
+    @Test
+    public void testInvalidFormat() throws URISyntaxException, IOException {
+        Path file = Paths
+                .get(MedlinePlainImporter.class.getResource("MedlinePlainImporterTestInvalidFormat.xml").toURI());
+        List<BibEntry> entries = importer.importDatabase(file, Charsets.UTF_8).getDatabase().getEntries();
+        assertEquals(Collections.emptyList(), entries);
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void testNullReader() throws IOException {
+        try (BufferedReader reader = null) {
+            importer.importDatabase(reader);
+        }
+        fail();
+    }
+
     @Test
     public void testAllArticleTypes() throws IOException {
         try (BufferedReader reader = readerForString("PMID-22664795" + "\n" +
diff --git a/src/test/resources/net/sf/jabref/importer/fileformat/MedlinePlainImporterStringOutOfBounds.bib b/src/test/resources/net/sf/jabref/importer/fileformat/MedlinePlainImporterStringOutOfBounds.bib
new file mode 100644
index 00000000000..005a90f4969
--- /dev/null
+++ b/src/test/resources/net/sf/jabref/importer/fileformat/MedlinePlainImporterStringOutOfBounds.bib
@@ -0,0 +1,5 @@
+@misc{,
+  title = {This is a test title}
+}, @misc{,
+  title = {This is also a test title}
+}
diff --git a/src/test/resources/net/sf/jabref/importer/fileformat/MedlinePlainImporterStringOutOfBounds.txt b/src/test/resources/net/sf/jabref/importer/fileformat/MedlinePlainImporterStringOutOfBounds.txt
new file mode 100644
index 00000000000..3337997b30f
--- /dev/null
+++ b/src/test/resources/net/sf/jabref/importer/fileformat/MedlinePlainImporterStringOutOfBounds.txt
@@ -0,0 +1,8 @@
+
+PMID- 27433151
+SO  invalid line
+TI  - This is a test title
+
+PMID- 27394443
+SO- another invalid line
+TI  -This is also a test title
diff --git a/src/test/resources/net/sf/jabref/importer/fileformat/MedlinePlainImporterTestInvalidFormat.xml b/src/test/resources/net/sf/jabref/importer/fileformat/MedlinePlainImporterTestInvalidFormat.xml
new file mode 100644
index 00000000000..62c549fdaf5
--- /dev/null
+++ b/src/test/resources/net/sf/jabref/importer/fileformat/MedlinePlainImporterTestInvalidFormat.xml
@@ -0,0 +1,5 @@
+PMC some PMC
+  PMID
+
+
+SO-something stands here
\ No newline at end of file