diff --git a/ndk/platforms/android-21/include/media/NdkMediaDrm.h b/ndk/platforms/android-21/include/media/NdkMediaDrm.h
index 10afdd9..3c312a9 100644
--- a/ndk/platforms/android-21/include/media/NdkMediaDrm.h
+++ b/ndk/platforms/android-21/include/media/NdkMediaDrm.h
@@ -327,24 +327,24 @@
 /**
  * String property name: identifies the maker of the DRM engine plugin
  */
-const char *PROPERTY_VENDOR = "vendor";
+#define PROPERTY_VENDOR "vendor"
 
 /**
  * String property name: identifies the version of the DRM engine plugin
  */
-const char *PROPERTY_VERSION = "version";
+#define PROPERTY_VERSION "version"
 
 /**
  * String property name: describes the DRM engine plugin
  */
-const char *PROPERTY_DESCRIPTION = "description";
+#define PROPERTY_DESCRIPTION "description"
 
 /**
  * String property name: a comma-separated list of cipher and mac algorithms
  * supported by CryptoSession.  The list may be empty if the DRM engine
  * plugin does not support CryptoSession operations.
  */
-const char *PROPERTY_ALGORITHMS = "algorithms";
+#define PROPERTY_ALGORITHMS "algorithms"
 
 /**
  * Read a DRM engine plugin String property value, given the property name string.
@@ -361,7 +361,7 @@
  * Byte array property name: the device unique identifier is established during
  * device provisioning and provides a means of uniquely identifying each device.
  */
-const char *PROPERTY_DEVICE_UNIQUE_ID = "deviceUniqueId";
+#define PROPERTY_DEVICE_UNIQUE_ID "deviceUniqueId"
 
 /**
  * Read a DRM engine plugin byte array property value, given the property name string.