diff --git a/src/main/java/com/android/tools/r8/dex/DexParser.java b/src/main/java/com/android/tools/r8/dex/DexParser.java
index 4524505..8042a1a 100644
--- a/src/main/java/com/android/tools/r8/dex/DexParser.java
+++ b/src/main/java/com/android/tools/r8/dex/DexParser.java
@@ -649,7 +649,7 @@
       ClassAccessFlags flags = ClassAccessFlags.fromDexAccessFlags(accessFlags[i]);
       // Check if constraints from
       // https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.1 are met.
-      if (!flags.areValid(Constants.CORRESPONDING_CLASS_FILE_VERSION)) {
+      if (!flags.areValid(Constants.CORRESPONDING_CLASS_FILE_VERSION, false)) {
         throw new CompilationError("Class " + type.toSourceString()
             + " has illegal access flags. Found: " + flags, origin);
       }
diff --git a/src/main/java/com/android/tools/r8/graph/ClassAccessFlags.java b/src/main/java/com/android/tools/r8/graph/ClassAccessFlags.java
index 0111aa1..4fce492 100644
--- a/src/main/java/com/android/tools/r8/graph/ClassAccessFlags.java
+++ b/src/main/java/com/android/tools/r8/graph/ClassAccessFlags.java
@@ -92,15 +92,16 @@
    * Checks whether the constraints from
    * https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.1 are met.
    */
-  public boolean areValid(int majorVersion) {
+  public boolean areValid(int majorVersion, boolean isPackageInfo) {
     if (isInterface()) {
       // We ignore the super flags prior to JDK 9, as so did the VM.
       if ((majorVersion >= 53) && isSuper()) {
         return false;
       }
-      // We require interfaces to be abstract from JDK 7 onwards. Old versions of javac seem to
-      // have produced package-info classes that are interfaces but not abstract.
-      if ((majorVersion >= 51) && (!isAbstract())) {
+      // We require interfaces to be abstract - except for package-info classes - as both old
+      // versions of javac and other tools can produce package-info classes that are interfaces but
+      // not abstract.
+      if (!isAbstract() && !isPackageInfo) {
         return false;
       }
       return !isFinal() && !isEnum();
diff --git a/src/main/java/com/android/tools/r8/graph/JarClassFileReader.java b/src/main/java/com/android/tools/r8/graph/JarClassFileReader.java
index 247f790..a1125af 100644
--- a/src/main/java/com/android/tools/r8/graph/JarClassFileReader.java
+++ b/src/main/java/com/android/tools/r8/graph/JarClassFileReader.java
@@ -244,6 +244,24 @@
               : new EnclosingMethodAttribute(application.getMethod(ownerType, name, desc));
     }
 
+    private String illegalClassFilePrefix(ClassAccessFlags accessFlags, String name) {
+      return "Illegal class file: "
+          + (accessFlags.isInterface() ? "Interface" : "Class")
+          + " "
+          + name;
+    }
+
+    private String illegalClassFilePostfix(int version) {
+      return "Class file version " + version;
+    }
+
+    private String illegalClassFileMessage(
+        ClassAccessFlags accessFlags, String name, int version, String message) {
+      return illegalClassFilePrefix(accessFlags, name)
+          + " " + message
+          + ". " + illegalClassFilePostfix(version) + ".";
+    }
+
     @Override
     public void visit(int version, int access, String name, String signature, String superName,
         String[] interfaces) {
@@ -252,18 +270,22 @@
       type = application.getTypeFromName(name);
       // Check if constraints from
       // https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.1 are met.
-      if (!accessFlags.areValid(getMajorVersion())) {
-        throw new CompilationError("Illegal class file: Class " + name
-            + " has invalid access flags. Found: " + accessFlags.toString(), origin);
+      if (!accessFlags.areValid(getMajorVersion(), name.endsWith("/package-info"))) {
+        throw new CompilationError(
+            illegalClassFileMessage(accessFlags, name, version,
+                "has invalid access flags. Found: " + accessFlags.toString()), origin);
       }
       if (superName == null && !name.equals(Constants.JAVA_LANG_OBJECT_NAME)) {
-        throw new CompilationError("Illegal class file: Class " + name
-            + " is missing a super type.", origin);
+        throw new CompilationError(
+            illegalClassFileMessage(accessFlags, name, version,
+                "is missing a super type"), origin);
       }
       if (accessFlags.isInterface()
           && !Objects.equals(superName, Constants.JAVA_LANG_OBJECT_NAME)) {
-        throw new CompilationError("Illegal class file: Interface " + name
-            + " must extend class java.lang.Object. Found: " + Objects.toString(superName), origin);
+        throw new CompilationError(
+            illegalClassFileMessage(accessFlags, name, version,
+                "must extend class java.lang.Object. Found: " + Objects.toString(superName)),
+            origin);
       }
       assert superName != null || name.equals(Constants.JAVA_LANG_OBJECT_NAME);
       superType = superName == null ? null : application.getTypeFromName(superName);