--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/tree/TreeInfo.java	Thu Mar 31 11:50:26 2016 -0700
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/tree/TreeInfo.java	Thu Mar 31 17:25:58 2016 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1152,7 +1152,8 @@
     }
 
     public static boolean isModuleInfo(JCCompilationUnit tree) {
-        return tree.sourcefile.isNameCompatible("module-info", JavaFileObject.Kind.SOURCE);
+        return tree.sourcefile.isNameCompatible("module-info", JavaFileObject.Kind.SOURCE)
+                && tree.defs.nonEmpty() && tree.defs.head.hasTag(MODULEDEF);
     }
 
     public static JCModuleDecl getModule(JCCompilationUnit t) {

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/modules/NPECompilingModuleInfoTest.java	Thu Mar 31 17:25:58 2016 -0400
@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * @test
+ * @bug 8150733
+ * @summary NPE when compiling module-info.java with a class declaration in a non-module mode
+ * @library /tools/lib
+ * @modules
+ *      jdk.compiler/com.sun.tools.javac.api
+ *      jdk.compiler/com.sun.tools.javac.main
+ *      jdk.jdeps/com.sun.tools.javap
+ * @build ToolBox ModuleTestBase
+ * @run main NPECompilingModuleInfoTest
+ */
+
+import java.nio.file.Path;
+
+import com.sun.source.util.JavacTask;
+
+public class NPECompilingModuleInfoTest extends ModuleTestBase {
+    public static void main(String... args) throws Exception {
+        new NPECompilingModuleInfoTest().runTests();
+    }
+
+    @Test
+    void testCompileNoError(Path base) throws Exception {
+        Path mod = base.resolve("mod");
+        tb.writeJavaFiles(mod, "module mod { exports pkg; }");
+        Path pkg = mod.resolve("pkg");
+        Path customClass = pkg.resolve("module-info.java");
+        tb.writeFile(customClass, "package pkg; class C {}");
+        Path classes = base.resolve("classes");
+        tb.createDirectories(classes);
+
+        tb.new JavacTask()
+                .outdir(classes)
+                .files(findJavaFiles(mod))
+                .run()
+                .writeAll()
+                .getOutputLines(ToolBox.OutputKind.DIRECT);
+    }
+}