diff --git a/aocsync.py b/aocsync.py
index b85cab4..71898d8 100755
--- a/aocsync.py
+++ b/aocsync.py
@@ -636,28 +636,29 @@ class CargoAOCRunner:
                 '-w', f'/repo/{work_dir_rel}',  # Working directory in container
             ]
             
-            # Handle cargo registry cache
+            # Handle cargo registry cache and cargo home
             if registry_cache_dir:
-                # Use persistent registry cache
+                # Use persistent registry cache - mount entire CARGO_HOME directory
                 registry_cache_path = Path(registry_cache_dir).resolve()
                 registry_cache_path.mkdir(parents=True, exist_ok=True)
-                podman_cmd.extend(['-v', f'{registry_cache_path}:/root/.cargo/registry:rw'])
-                logger.info(f"Using persistent registry cache: {registry_cache_path}")
+                # Mount the parent directory as CARGO_HOME so both registry and bin are persisted
+                cargo_home_path = registry_cache_path.parent / 'cargo-home'
+                cargo_home_path.mkdir(parents=True, exist_ok=True)
+                podman_cmd.extend(['-v', f'{cargo_home_path}:/root/.cargo:rw'])
+                logger.info(f"Using persistent cargo home (registry + bin): {cargo_home_path}")
             else:
-                # Use tmpfs for registry cache (cleared after each run)
-                podman_cmd.extend(['--tmpfs', '/root/.cargo/registry:rw,noexec,nosuid,size=100m'])
+                # Use tmpfs for cargo home (cleared after each run)
+                podman_cmd.extend(['--tmpfs', '/root/.cargo:rw,noexec,nosuid,size=200m'])
             
-            # Handle cargo-aoc installation location (only needed if installing on-the-fly)
-            if needs_cargo_aoc_install:
-                # Need writable /root/.cargo/bin to install cargo-aoc
-                if registry_cache_dir:
-                    # If using persistent registry cache, also persist cargo bin
-                    cargo_bin_path = Path(registry_cache_dir).parent / 'cargo-bin'
-                    cargo_bin_path.mkdir(parents=True, exist_ok=True)
-                    podman_cmd.extend(['-v', f'{cargo_bin_path}:/root/.cargo/bin:rw'])
-                else:
-                    # Use tmpfs for cargo bin (will be cleared, but allows installation)
-                    podman_cmd.extend(['--tmpfs', '/root/.cargo/bin:rw,noexec,nosuid,size=50m'])
+            # Note: cargo-aoc installation location is handled above via CARGO_HOME mount
+            # If using persistent cache, cargo bin is already mounted via cargo-home
+            # If using tmpfs, cargo bin is already included in /root/.cargo tmpfs
+            
+            # Set environment variables in the container so cargo uses the mounted directories
+            # Set build directory (target directory for compiled artifacts)
+            podman_cmd.extend(['-e', 'CARGO_TARGET_DIR=/build/target'])
+            # Set cargo home to use the mounted registry cache
+            podman_cmd.extend(['-e', 'CARGO_HOME=/root/.cargo'])
             
             # Add Podman image and command
             if needs_cargo_aoc_install:
@@ -674,16 +675,11 @@ class CargoAOCRunner:
                     'cargo', 'aoc', '--day', str(day)
                 ])
             
-            # Set CARGO_TARGET_DIR to use the mounted build directory
-            env = os.environ.copy()
-            env['CARGO_TARGET_DIR'] = '/build/target'
-            
             result = subprocess.run(
                 podman_cmd,
                 capture_output=True,
                 text=True,
-                timeout=300,  # 5 minute timeout
-                env=env
+                timeout=300  # 5 minute timeout
             )
             
             return result