diff --git a/lib/lint.ml b/lib/lint.ml
index db2b54d..067cb0e 100644
--- a/lib/lint.ml
+++ b/lib/lint.ml
@@ -257,7 +257,7 @@ module Checks = struct
               if OpamVersionCompare.compare dep ver >= 0 then []
               else [ (pkg, BadDuneConstraint (dep, ver)) ]
         in
-        if is_build then [ (pkg, DuneIsBuild) ] else errors
+        if is_build then (pkg, DuneIsBuild) :: errors else errors
     | None -> []
 
   let check_maintainer_email ~pkg opam =
diff --git a/test/lint.t b/test/lint.t
index 458e1eb..9870736 100644
--- a/test/lint.t
+++ b/test/lint.t
@@ -63,6 +63,7 @@ Test the following:
   Linting opam-repository at $TESTCASE_ROOT/. ...
   Warning in b.0.0.2: Dubious use of 'dune subst'. 'dune subst' should always only be called with {dev} (i.e. ["dune" "subst"] {dev}) If your opam file has been autogenerated by dune, you need to upgrade your dune-project to at least (lang dune 2.7).
   Warning in b.0.0.2: The package tagged dune as a build dependency. Due to a bug in dune (https://github.com/ocaml/dune/issues/2147) this should never be the case. Please remove the {build} tag from its filter.
+  Error in b.0.0.2: Failed to download the archive. Details: $TESTCASE_ROOT/b.0.0.2.tgz
   Error in b.0.0.2:              error  3: File format error in 'unknown-field' at line 11, column 0: Invalid field unknown-field
   Error in b.0.0.2:              error 60: Upstream check failed: "Source not found: $TESTCASE_ROOT/b.0.0.2.tgz"
   [1]
diff --git a/test/patches/b-incorrect-opam.patch b/test/patches/b-incorrect-opam.patch
index f6677a0..d05f029 100644
--- a/test/patches/b-incorrect-opam.patch
+++ b/test/patches/b-incorrect-opam.patch
@@ -39,7 +39,7 @@ index 0000000..a47aabf
 +  ["dune" "subst"]
 +]
 +url {
-+  src: "./b.0.0.2.tgz"
++  src: "b.0.0.2.tgz"
 +  checksum: ["sha256=e26dfd7fa9731d0d43239c8b7d36bd3d79b0f709f1cdfa2ada7a7ab5d79d1911"]
 +}
 +depends: [