diff --git a/lib/manager/dockerfile/__fixtures__/2.Dockerfile b/lib/manager/dockerfile/__fixtures__/2.Dockerfile
index 7d183600c45086ea52caa5585a3e088f1790286c..6ea296ec1cef31807abfa9c8e08fdaf0662104d3 100644
--- a/lib/manager/dockerfile/__fixtures__/2.Dockerfile
+++ b/lib/manager/dockerfile/__fixtures__/2.Dockerfile
@@ -7,7 +7,7 @@ FROM image2:1.0.0@sha256:abcdef \
 # FROM image3
 
 FROM\
-    --platform=linux \
+    --platform=$arg \
 	# comment1
 	 image4
 
diff --git a/lib/manager/dockerfile/extract.ts b/lib/manager/dockerfile/extract.ts
index b79219537969f3d0a7616678ac39a8be6c4d3a98..eb0bacfae270674e30391a39156e12598fc3aab5 100644
--- a/lib/manager/dockerfile/extract.ts
+++ b/lib/manager/dockerfile/extract.ts
@@ -90,7 +90,7 @@ export function extractPackageFile(content: string): PackageFile | null {
   const stageNames: string[] = [];
 
   const fromMatches = content.matchAll(
-    /^[ \t]*FROM(?:\\\r?\n| |\t|#.*?\r?\n|[ \t]--[a-z]+=\w+?)*[ \t](?<image>\S+)(?:(?:\\\r?\n| |\t|#.*\r?\n)+as[ \t]+(?<name>\S+))?/gim // TODO #12070
+    /^[ \t]*FROM(?:\\\r?\n| |\t|#.*?\r?\n|[ \t]--[a-z]+=\S+?)*[ \t](?<image>\S+)(?:(?:\\\r?\n| |\t|#.*\r?\n)+as[ \t]+(?<name>\S+))?/gim // TODO #12070
   );
 
   for (const fromMatch of fromMatches) {