diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 06a993240..a2c375873 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -16,7 +16,7 @@ jobs:
         uses: actions/checkout@master
         with:
           path: rgbds
-          ref: v0.8.0
+          ref: v0.9.0
           repository: gbdev/rgbds
 
       - name: Install rgbds
diff --git a/INSTALL.md b/INSTALL.md
index 78cc93191..7b6a8520b 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -42,9 +42,9 @@ Run setup and leave the default settings. At the "**Select Packages**" step, cho
 
 Double click on the text that says "**Skip**" next to each package to select the most recent version to install.
 
-Then follow the [**rgbds** install instructions](https://rgbds.gbdev.io/install#pre-built) for Windows with Cygwin to install **rgbds 0.7.0**.
+Then follow the [**rgbds** install instructions](https://rgbds.gbdev.io/install#pre-built) for Windows with Cygwin to install **rgbds 0.9.0**.
 
-**Note:** If you already have an installed rgbds older than 0.7.0, you will need to update to 0.7.0. Ignore this if you have never installed rgbds before. If a version newer than 0.7.0 does not work, try downloading 0.7.0.
+**Note:** If you already have an installed rgbds older than 0.9.0, you will need to update to 0.9.0. Ignore this if you have never installed rgbds before. If a version newer than 0.9.0 does not work, try downloading 0.9.0.
 
 Now open the **Cygwin terminal** and enter the following commands.
 
@@ -67,7 +67,7 @@ Install [**Homebrew**](https://brew.sh/). Follow the official instructions.
 
 Open **Terminal** and prepare to enter commands.
 
-Then follow the [**rgbds** instructions](https://rgbds.gbdev.io/install#pre-built) for macOS to install **rgbds 0.7.0**.
+Then follow the [**rgbds** instructions](https://rgbds.gbdev.io/install#pre-built) for macOS to install **rgbds 0.9.0**.
 
 Now you're ready to [build **pokeyellow**](#build-pokeyellow).
 
@@ -84,7 +84,7 @@ To install the software required for **pokeyellow**:
 sudo apt-get install make gcc git
 ```
 
-Then follow the [**rgbds** instructions](https://rgbds.gbdev.io/install#building-from-source) to build **rgbds 0.7.0** from source.
+Then follow the [**rgbds** instructions](https://rgbds.gbdev.io/install#building-from-source) to build **rgbds 0.9.0** from source.
 
 ### OpenSUSE
 
@@ -94,7 +94,7 @@ To install the software required for **pokeyellow**:
 sudo zypper install make gcc git
 ```
 
-Then follow the [**rgbds** instructions](https://rgbds.gbdev.io/install#building-from-source) to build **rgbds 0.7.0** from source.
+Then follow the [**rgbds** instructions](https://rgbds.gbdev.io/install#building-from-source) to build **rgbds 0.9.0** from source.
 
 ### Arch Linux
 
@@ -104,7 +104,7 @@ To install the software required for **pokeyellow**:
 sudo pacman -S make gcc git rgbds
 ```
 
-If you want to compile and install **rgbds** yourself instead, then follow the [**rgbds** instructions](https://rgbds.gbdev.io/install#building-from-source) to build **rgbds 0.7.0** from source.
+If you want to compile and install **rgbds** yourself instead, then follow the [**rgbds** instructions](https://rgbds.gbdev.io/install#building-from-source) to build **rgbds 0.9.0** from source.
 
 ### Termux
 
@@ -120,7 +120,7 @@ To install **rgbds**:
 sudo apt install rgbds
 ```
 
-If you want to compile and install **rgbds** yourself instead, then follow the [**rgbds** instructions](https://rgbds.gbdev.io/install#building-from-source) to build **rgbds 0.7.0** from source.
+If you want to compile and install **rgbds** yourself instead, then follow the [**rgbds** instructions](https://rgbds.gbdev.io/install#building-from-source) to build **rgbds 0.9.0** from source.
 
 ### Other distros
 
@@ -131,7 +131,7 @@ If your distro is not listed here, try to find the required software in its repo
 - `git`
 - `rgbds`
 
-If `rgbds` is not available, you'll need to follow the [**rgbds** instructions](https://rgbds.gbdev.io/install#building-from-source) to build **rgbds 0.7.0** from source.
+If `rgbds` is not available, you'll need to follow the [**rgbds** instructions](https://rgbds.gbdev.io/install#building-from-source) to build **rgbds 0.9.0** from source.
 
 Now you're ready to [build **pokeyellow**](#build-pokeyellow).
 
@@ -153,8 +153,8 @@ make
 
 ### Build with a local rgbds version
 
-If you have different projects that require different versions of `rgbds`, it might not be convenient to install rgbds 0.7.0 globally. Instead, you can put its files in a directory within pokeyellow, such as `pokeyellow/rgbds-0.7.0/`. Then specify it when you run `make`:
+If you have different projects that require different versions of `rgbds`, it might not be convenient to install rgbds 0.9.0 globally. Instead, you can put its files in a directory within pokeyellow, such as `pokeyellow/rgbds-0.9.0/`. Then specify it when you run `make`:
 
 ```bash
-make RGBDS=rgbds-0.7.0/
+make RGBDS=rgbds-0.9.0/
 ```
diff --git a/Makefile b/Makefile
index 187be1e35..144cb9841 100644
--- a/Makefile
+++ b/Makefile
@@ -130,7 +130,7 @@ pokeyellow_pad       = 0x00
 pokeyellow_debug_pad = 0xff
 pokeyellow_vc_pad    = 0x00
 
-opts = -cjsv -k 01 -l 0x33 -m 0x1b -p 0 -r 03 -t "POKEMON YELLOW"
+opts = -cjsv -k 01 -l 0x33 -m MBC5+RAM+BATTERY -p 0 -r 03 -t "POKEMON YELLOW"
 
 %.gbc: $$(%_obj) layout.link
 	$(RGBLINK) -p $($*_pad) -w -m $*.map -n $*.sym -l layout.link -o $@ $(filter %.o,$^)
diff --git a/engine/battle/animations.asm b/engine/battle/animations.asm
index f9608fdb4..33036d05c 100644
--- a/engine/battle/animations.asm
+++ b/engine/battle/animations.asm
@@ -1829,8 +1829,7 @@ AnimationMinimizeMon:
 
 MinimizedMonSprite:
 ; 8x5 partial tile graphic
-pusho
-opt b.X ; . = 0, X = 1
+pusho b.X ; . = 0, X = 1
 	db %...XX...
 	db %..XXXX..
 	db %.XXXXXX.
diff --git a/rgbdscheck.asm b/rgbdscheck.asm
index ed9e6d3b4..d6789e646 100644
--- a/rgbdscheck.asm
+++ b/rgbdscheck.asm
@@ -1,6 +1,6 @@
 IF !DEF(__RGBDS_MAJOR__) || !DEF(__RGBDS_MINOR__) || !DEF(__RGBDS_PATCH__)
-	fail "pokeyellow requires rgbds v0.7.0 or newer."
+	fail "pokeyellow requires rgbds v0.9.0 or newer."
 ENDC
-IF __RGBDS_MAJOR__ == 0 && __RGBDS_MINOR__ <  7
-	fail "pokeyellow requires rgbds v0.7.0 or newer."
+IF __RGBDS_MAJOR__ == 0 && __RGBDS_MINOR__ < 9
+	fail "pokeyellow requires rgbds v0.9.0 or newer."
 ENDC
diff --git a/tools/unnamed.py b/tools/unnamed.py
index 70ff2352b..4e8811bec 100755
--- a/tools/unnamed.py
+++ b/tools/unnamed.py
@@ -90,14 +90,14 @@ def read_string(file):
 		elif magic == b'RGB9':
 			obj_ver = 10 + unpack_from('<I', file)[0]
 
-		if obj_ver not in [6, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20]:
+		if obj_ver not in [6, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 21]:
 			print(f"Error: File '{objfile}' is of an unknown format.", file=sys.stderr)
 			sys.exit(1)
 
 		num_symbols = unpack_from('<I', file)[0]
 		unpack_from('<I', file) # skip num sections
 
-		if obj_ver in [16, 17, 18, 19, 20]:
+		if obj_ver in [16, 17, 18, 19, 20, 21]:
 			node_filenames = []
 			num_nodes = unpack_from('<I', file)[0]
 			for x in range(num_nodes):
@@ -117,7 +117,7 @@ def read_string(file):
 			sym_type = symtype(unpack_from('<B', file)[0] & 0x7f)
 			if sym_type == symtype.IMPORT:
 				continue
-			if obj_ver in [16, 17, 18, 19, 20]:
+			if obj_ver in [16, 17, 18, 19, 20, 21]:
 				sym_fileno = unpack_from('<I', file)[0]
 				sym_filename = node_filenames[sym_fileno]
 			else: