diff --git a/backend/build_binary.py b/backend/build_binary.py
index 2df2ceb2..875d6733 100644
--- a/backend/build_binary.py
+++ b/backend/build_binary.py
@@ -55,20 +55,23 @@ def build_server(cuda=False):
     # numpy 2.x / torch ABI mismatch fix: install memmove fallback for
     # torch.from_numpy() before the app starts. Runtime hooks run after
     # FrozenImporter is registered so frozen torch/numpy are importable.
+    # Paths are passed relative to backend_dir because os.chdir(backend_dir)
+    # runs before PyInstaller. Absolute paths would get baked into the
+    # generated .spec, breaking reproducible builds on other machines / CI.
     args.extend(
         [
             "--runtime-hook",
-            str(backend_dir / "pyi_rth_numpy_compat.py"),
+            "pyi_rth_numpy_compat.py",
             # Stub torch.compiler.disable before transformers imports
             # flex_attention, which otherwise triggers torch._dynamo →
             # torch._numpy._ufuncs and crashes at module load under
             # PyInstaller. See pyi_rth_torch_compiler_disable.py.
             "--runtime-hook",
-            str(backend_dir / "pyi_rth_torch_compiler_disable.py"),
+            "pyi_rth_torch_compiler_disable.py",
             # Per-module collection overrides (e.g. forcing scipy.stats._distn_infrastructure
             # to bundle .py source alongside .pyc so the runtime hook can source-patch it).
             "--additional-hooks-dir",
-            str(backend_dir / "pyi_hooks"),
+            "pyi_hooks",
         ]
     )
 
diff --git a/backend/voicebox-server.spec b/backend/voicebox-server.spec
index 4f7f49b7..ab8566c8 100644
--- a/backend/voicebox-server.spec
+++ b/backend/voicebox-server.spec
@@ -58,9 +58,9 @@ a = Analysis(
     binaries=binaries,
     datas=datas,
     hiddenimports=hiddenimports,
-    hookspath=['/Users/jamie/Projects/spacedriveapp/voicebox/backend/pyi_hooks'],
+    hookspath=['pyi_hooks'],
     hooksconfig={},
-    runtime_hooks=['/Users/jamie/Projects/spacedriveapp/voicebox/backend/pyi_rth_numpy_compat.py', '/Users/jamie/Projects/spacedriveapp/voicebox/backend/pyi_rth_torch_compiler_disable.py'],
+    runtime_hooks=['pyi_rth_numpy_compat.py', 'pyi_rth_torch_compiler_disable.py'],
     excludes=['nvidia', 'nvidia.cublas', 'nvidia.cuda_cupti', 'nvidia.cuda_nvrtc', 'nvidia.cuda_runtime', 'nvidia.cudnn', 'nvidia.cufft', 'nvidia.curand', 'nvidia.cusolver', 'nvidia.cusparse', 'nvidia.nccl', 'nvidia.nvjitlink', 'nvidia.nvtx'],
     noarchive=False,
     optimize=0,