diff --git a/NEWS b/NEWS
index 9933fd21d..64e8b825b 100644
--- a/NEWS
+++ b/NEWS
@@ -38,6 +38,13 @@ ver 0.22 (not yet released)
 * switch to C++17
   - GCC 7 or clang 4 (or newer) recommended
 
+ver 0.21.24 (not yet released)
+* protocol
+  - "tagtypes" requires no permissions
+* database
+  - simple: fix crash when mounting twice
+* fix unit test failure
+
 ver 0.21.23 (2020/04/23)
 * protocol
   - add tag fallback for AlbumSort
diff --git a/android/AndroidManifest.xml b/android/AndroidManifest.xml
index 64d0802b1..bde283bce 100644
--- a/android/AndroidManifest.xml
+++ b/android/AndroidManifest.xml
@@ -2,8 +2,8 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
           package="org.musicpd"
           android:installLocation="auto"
-          android:versionCode="46"
-          android:versionName="0.21.23">
+          android:versionCode="47"
+          android:versionName="0.21.24">
 
   <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="28"/>
 
diff --git a/src/command/AllCommands.cxx b/src/command/AllCommands.cxx
index 8797543a6..560d69c87 100644
--- a/src/command/AllCommands.cxx
+++ b/src/command/AllCommands.cxx
@@ -201,7 +201,7 @@ static constexpr struct command commands[] = {
 	{ "subscribe", PERMISSION_READ, 1, 1, handle_subscribe },
 	{ "swap", PERMISSION_CONTROL, 2, 2, handle_swap },
 	{ "swapid", PERMISSION_CONTROL, 2, 2, handle_swapid },
-	{ "tagtypes", PERMISSION_READ, 0, -1, handle_tagtypes },
+	{ "tagtypes", PERMISSION_NONE, 0, -1, handle_tagtypes },
 	{ "toggleoutput", PERMISSION_ADMIN, 1, 1, handle_toggleoutput },
 #ifdef ENABLE_DATABASE
 	{ "unmount", PERMISSION_ADMIN, 1, 1, handle_unmount },
diff --git a/src/db/plugins/simple/SimpleDatabasePlugin.cxx b/src/db/plugins/simple/SimpleDatabasePlugin.cxx
index b9bdeff55..c0dff9cc2 100644
--- a/src/db/plugins/simple/SimpleDatabasePlugin.cxx
+++ b/src/db/plugins/simple/SimpleDatabasePlugin.cxx
@@ -448,12 +448,7 @@ SimpleDatabase::Mount(const char *local_uri, const char *storage_uri)
 
 	// TODO: update the new database instance?
 
-	try {
-		Mount(local_uri, std::move(db));
-	} catch (...) {
-		db->Close();
-		throw;
-	}
+	Mount(local_uri, std::move(db));
 }
 
 inline DatabasePtr
diff --git a/src/player/CrossFade.cxx b/src/player/CrossFade.cxx
index 7c9ece160..e5611f97c 100644
--- a/src/player/CrossFade.cxx
+++ b/src/player/CrossFade.cxx
@@ -62,7 +62,7 @@ mixramp_interpolate(const char *ramp_list, float required_db) noexcept
 			++ramp_list;
 
 		/* Check for exact match. */
-		if (db >= required_db) {
+		if (db == required_db) {
 			return duration;
 		}
 
diff --git a/src/util/Math.hxx b/src/util/Math.hxx
index ad5cffd82..28f50c6cc 100644
--- a/src/util/Math.hxx
+++ b/src/util/Math.hxx
@@ -36,7 +36,7 @@
  * C99 math can be optionally omitted with gcc's libstdc++.
  * Use boost if unavailable.
  */
-#if (defined(__GLIBCPP__) || defined(__GLIBCXX__)) && !defined(_GLIBCXX_USE_C99_MATH)
+#if (defined(__GLIBCPP__) || defined(__GLIBCXX__)) && !defined(_GLIBCXX_USE_C99_MATH_TR1)
 #include <boost/math/special_functions/round.hpp>
 using boost::math::lround;
 #else