diff --git a/Packaging/OpenDingux/build.sh b/Packaging/OpenDingux/build.sh
index 9eb016fe9..cdaeac663 100755
--- a/Packaging/OpenDingux/build.sh
+++ b/Packaging/OpenDingux/build.sh
@@ -41,7 +41,6 @@ declare BUILD_TYPE=release
 
 main() {
 	parse_args "$@"
-	BUILD_DIR="build-${TARGET}"
 	BUILDROOT_TARGET="$TARGET"
 
 	# If a TOOLCHAIN environment variable is set, just use that.
@@ -100,6 +99,7 @@ parse_args() {
 		exit 64
 	fi
 	TARGET="${positional[0]}"
+	BUILD_DIR="build-${TARGET}"
 
 	if (( PROFILE_GENERATE )) && (( PROFILE_USE )); then
 		>&2 echo "Error: at most one of --profile-use and --profile-generate is allowed"
@@ -115,9 +115,19 @@ parse_args() {
 		OPK_EXTRA_FILES=(
 			Packaging/OpenDingux/profile-generate.sh
 			test/fixtures/timedemo/WarriorLevel1to2/demo_0.dmo
+		)
+		local -a demo_saves=(
 			test/fixtures/timedemo/WarriorLevel1to2/demo_0_reference_spawn_0.sv
 			test/fixtures/timedemo/WarriorLevel1to2/spawn_0.sv
 		)
+		if [[ $TARGET = rg99 ]]; then
+			# We use unpacked saves on RG99.
+			mkdir -p "$BUILD_DIR/demo-saves"
+			unpack_and_minify_mpq --output-dir "$BUILD_DIR/demo-saves" "${demo_saves[@]}"
+			OPK_EXTRA_FILES+=("$BUILD_DIR/demo-saves"/*)
+		else
+			OPK_EXTRA_FILES+=("${demo_saves[@]}")
+		fi
 	fi
 	if (( PROFILE_USE )); then
 		CMAKE_CONFIGURE_OPTS+=(
diff --git a/Packaging/OpenDingux/profile-generate.sh b/Packaging/OpenDingux/profile-generate.sh
index 67c63676a..ee3067f45 100755
--- a/Packaging/OpenDingux/profile-generate.sh
+++ b/Packaging/OpenDingux/profile-generate.sh
@@ -3,8 +3,8 @@
 set -x
 
 SAVE_DIR="$(mktemp -d)"
-ln -s "${PWD}/demo_0_reference_spawn_0.sv" "${SAVE_DIR}/"
+ln -s "${PWD}/demo_0_reference_spawn_0_sv" "${SAVE_DIR}/"
 ln -s "${PWD}/demo_0.dmo" "${SAVE_DIR}/"
-cp "${PWD}/spawn_0.sv" "${SAVE_DIR}/"
+cp -r "${PWD}/spawn_0_sv" "${SAVE_DIR}/"
 ./devilutionx --diablo --spawn --demo 0 --timedemo --save-dir "$SAVE_DIR" --data-dir ~/.local/share/diasurgical/devilution
 rm -rf "$SAVE_DIR"
diff --git a/Packaging/OpenDingux/rg99-pgo.md b/Packaging/OpenDingux/rg99-pgo.md
new file mode 100644
index 000000000..f03e0492e
--- /dev/null
+++ b/Packaging/OpenDingux/rg99-pgo.md
@@ -0,0 +1,37 @@
+# RG99 profile-guided optimization
+
+The RG99 build must be PGO'd for reasonable performance.
+
+Here are the instructions for producing a PGO'd build.
+
+1.  Install <https://github.com/diasurgical/devilutionx-mpq-tools>
+
+2.  Build the OPK for profiling data collection:
+
+    ```sh
+    TOOLCHAIN=/opt/rs90-toolchain Packaging/OpenDingux/build.sh rg99 --profile-generate
+    ```
+
+3.  Copy the OPK to RG99 (`rg99` is 10.1.1.3):
+
+    ```sh
+    scp -O build-rg99/devilutionx-rg99.opk rg99:/media/sdcard/apps
+    ```
+
+4.  Now, run the OPK. It will run the timedemo instead of the actual game and will take about 1 hour (due to heavy swapping).
+
+
+5.  Copy the profiling data from RG99:
+
+    ```sh
+    rm -rf /tmp/devilutionx-profile
+    scp -r -O rg99:/media/data/local/home/devilutionx-profile /tmp/devilutionx-profile
+    ```
+
+6.  Build the OPK use the collected profiling data:
+
+    ```sh
+    TOOLCHAIN=/opt/rs90-toolchain Packaging/OpenDingux/build.sh rg99 --profile-use --profile-dir /tmp/devilutionx-profile
+    ```
+
+7.  The final package is at `build-rg99/devilutionx-rg99.opk`.