diff --git a/tools/gen_jarjar.py b/tools/gen_jarjar.py
index 4c2cf54..2ff53fa 100755
--- a/tools/gen_jarjar.py
+++ b/tools/gen_jarjar.py
@@ -115,7 +115,8 @@
             jar_classes = _list_jar_classes(jar)
             jar_classes.sort()
             for clazz in jar_classes:
-                if (_get_toplevel_class(clazz) not in excluded_classes and
+                if (not clazz.startswith(args.prefix + '.') and
+                        _get_toplevel_class(clazz) not in excluded_classes and
                         not any(r.fullmatch(clazz) for r in exclude_regexes)):
                     outfile.write(f'rule {clazz} {args.prefix}.@0\n')
                     # Also include jarjar rules for unit tests of the class, so the package matches
diff --git a/tools/testdata/java/jarjar/prefix/AlreadyInTargetPackageClass.java b/tools/testdata/java/jarjar/prefix/AlreadyInTargetPackageClass.java
new file mode 100644
index 0000000..6859020
--- /dev/null
+++ b/tools/testdata/java/jarjar/prefix/AlreadyInTargetPackageClass.java
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package jarjar.prefix;
+
+/**
+ * Sample class to test jarjar rules, already in the "jarjar.prefix" package.
+ */
+public class AlreadyInTargetPackageClass {
+    /** Test inner class that should not be jarjared either */
+    public static class TestInnerClass {}
+}