diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9b4b3458..eaee9923 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -61,6 +61,16 @@ set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_EXTENSIONS ON)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
+# Opt-in ccache launcher. The game sources are frozen (1:1 with the decomp),
+# so ccache makes branch-switch / worktree rebuilds nearly free. No-op when
+# ccache is not installed.
+find_program(CCACHE_PROGRAM ccache)
+if(CCACHE_PROGRAM)
+  set(CMAKE_C_COMPILER_LAUNCHER "${CCACHE_PROGRAM}")
+  set(CMAKE_CXX_COMPILER_LAUNCHER "${CCACHE_PROGRAM}")
+  message(STATUS "ccache enabled: ${CCACHE_PROGRAM}")
+endif()
+
 # Default build type
 if(NOT CMAKE_BUILD_TYPE AND NOT EXISTS ${CMAKE_BINARY_DIR}/CMakeCache.txt)
   set(CMAKE_BUILD_TYPE "RelWithDebInfo" CACHE STRING "" FORCE)
diff --git a/build-pc.sh b/build-pc.sh
index 8f71030f..34a6388c 100644
--- a/build-pc.sh
+++ b/build-pc.sh
@@ -22,7 +22,7 @@
 set -euo pipefail
 
 ROMID="${1:-ntsc-final}"
-BUILD_DIR="build-pc"
+BUILD_DIR="${BUILD_DIR:-build-pc}"
 
 echo "==> Configuring PC port (ROMID=${ROMID})"
 cmake -S . -B "${BUILD_DIR}" -DROMID="${ROMID}"