diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 65f74cc..5cbecae 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -29,6 +29,9 @@ jobs:
       - name: Verify accessible SVG contract
         run: python3 scripts/test-lint-a11y.py
 
+      - name: Verify Devicon normalization
+        run: python3 scripts/test-build-icons-devicon.py
+
       - name: Run skin linter
         run: python3 scripts/lint-skin.py --all --baseline
 
diff --git a/scripts/build-icons.py b/scripts/build-icons.py
index b191b2a..e78045b 100644
--- a/scripts/build-icons.py
+++ b/scripts/build-icons.py
@@ -292,6 +292,10 @@ def normalize_url(raw: str) -> str:
 def normalize_devicon(raw: str) -> str:
     """Devicon SVGs have colored fills and a 128x128 or 32x32 viewBox.
     Strip fills/classes and rewrite to 24x24 currentColor."""
+    viewbox_match = re.search(
+        r'\bviewBox\s*=\s*(["\'])(.*?)\1', raw, flags=re.IGNORECASE
+    )
+    viewbox = viewbox_match.group(2).strip() if viewbox_match else "0 0 128 128"
     inner = re.search(r"<svg\b[^>]*>(.*?)</svg>", raw, flags=re.DOTALL | re.IGNORECASE)
     if not inner:
         raise ValueError("no <svg> in Devicon payload")
@@ -303,7 +307,7 @@ def normalize_devicon(raw: str) -> str:
     body = re.sub(r'\bclass="[^"]*"', 'fill="currentColor"', body)
     body = re.sub(r"\s+", " ", body).strip()
     return (
-        '<svg aria-hidden="true" width="24" height="24" viewBox="0 0 128 128" '
+        f'<svg aria-hidden="true" width="24" height="24" viewBox="{viewbox}" '
         f'fill="currentColor">{body}</svg>'
     )
 
diff --git a/scripts/test-build-icons-devicon.py b/scripts/test-build-icons-devicon.py
new file mode 100755
index 0000000..ecb57e5
--- /dev/null
+++ b/scripts/test-build-icons-devicon.py
@@ -0,0 +1,40 @@
+#!/usr/bin/env python3
+"""Regression tests for Devicon viewBox preservation."""
+
+from __future__ import annotations
+
+import importlib.util
+import sys
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parent.parent
+BUILD = ROOT / "scripts" / "build-icons.py"
+
+
+def load_build_module():
+    sys.dont_write_bytecode = True
+    spec = importlib.util.spec_from_file_location("diagram_design_build_icons", BUILD)
+    if spec is None or spec.loader is None:
+        raise AssertionError("could not load build-icons.py")
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
+def main() -> int:
+    build_icons = load_build_module()
+    svg = '<svg viewBox="0 0 32 32"><path fill="#123456" d="M0 0h32v32H0z"/></svg>'
+    normalized = build_icons.normalize_devicon(svg)
+    if 'viewBox="0 0 32 32"' not in normalized:
+        raise AssertionError(f"source viewBox was not preserved: {normalized}")
+    if 'fill="#123456"' in normalized:
+        raise AssertionError("source fill escaped currentColor normalization")
+    if 'fill="currentColor"' not in normalized:
+        raise AssertionError("normalized icon does not inherit currentColor")
+    print("PASS: Devicon normalization preserves non-128 source viewBoxes")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())