diff --git a/pkgs/test/nixpkgs-check-by-name/Cargo.lock b/pkgs/test/nixpkgs-check-by-name/Cargo.lock
index b02f7075ab61..19435c2ab76e 100644
--- a/pkgs/test/nixpkgs-check-by-name/Cargo.lock
+++ b/pkgs/test/nixpkgs-check-by-name/Cargo.lock
@@ -306,6 +306,7 @@ dependencies = [
  "serde_json",
  "temp-env",
  "tempfile",
+ "textwrap",
 ]
 
 [[package]]
@@ -489,6 +490,12 @@ version = "1.11.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "942b4a808e05215192e39f4ab80813e599068285906cc91aa64f923db842bd5a"
 
+[[package]]
+name = "smawk"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b7c388c1b5e93756d0c740965c41e8822f866621d41acbdf6336a6a168f8840c"
+
 [[package]]
 name = "strsim"
 version = "0.10.0"
@@ -534,12 +541,35 @@ version = "1.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f18aa187839b2bdb1ad2fa35ead8c4c2976b64e4363c386d45ac0f7ee85c9233"
 
+[[package]]
+name = "textwrap"
+version = "0.16.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "23d434d3f8967a09480fb04132ebe0a3e088c173e6d0ee7897abbdf4eab0f8b9"
+dependencies = [
+ "smawk",
+ "unicode-linebreak",
+ "unicode-width",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "301abaae475aa91687eb82514b328ab47a211a533026cb25fc3e519b86adfc3c"
 
+[[package]]
+name = "unicode-linebreak"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3b09c83c3c29d37506a3e260c08c03743a6bb66a9cd432c6934ab501a190571f"
+
+[[package]]
+name = "unicode-width"
+version = "0.1.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e51733f11c9c4f72aa0c160008246859e340b00807569a0da0e7a1079b27ba85"
+
 [[package]]
 name = "utf8parse"
 version = "0.2.1"
diff --git a/pkgs/test/nixpkgs-check-by-name/Cargo.toml b/pkgs/test/nixpkgs-check-by-name/Cargo.toml
index 1b8f8e9085d4..50cdabb7e2dd 100644
--- a/pkgs/test/nixpkgs-check-by-name/Cargo.toml
+++ b/pkgs/test/nixpkgs-check-by-name/Cargo.toml
@@ -17,6 +17,7 @@ itertools = "0.11.0"
 rowan = "0.15.11"
 indoc = "2.0.4"
 relative-path = "1.9.2"
+textwrap = "0.16.1"
 
 [dev-dependencies]
 temp-env = "0.3.5"
diff --git a/pkgs/test/nixpkgs-check-by-name/src/nixpkgs_problem.rs b/pkgs/test/nixpkgs-check-by-name/src/nixpkgs_problem.rs
index dda89895697f..d8ae2db4dc22 100644
--- a/pkgs/test/nixpkgs-check-by-name/src/nixpkgs_problem.rs
+++ b/pkgs/test/nixpkgs-check-by-name/src/nixpkgs_problem.rs
@@ -188,28 +188,50 @@ impl fmt::Display for NixpkgsProblem {
                     "
                     - Because {} exists, the attribute `pkgs.{package_name}` must be defined like
 
-                        {package_name} = callPackage {} {{ /* ... */ }}
+                        {package_name} = callPackage {} {{ /* ... */ }};
 
                       This is however not the case: The first `callPackage` argument is the wrong path.
                       It is defined in {}:{}:{} as
 
-                        {package_name} = callPackage {} {{ /* ... */ }}",
+                        {package_name} = callPackage {} {{ /* ... */ }};",
                     structure::relative_dir_for_package(package_name).display(),
                     create_path_expr(file, expected_path),
                     file.display(), line, column,
                     create_path_expr(file, actual_path),
                 },
-            NixpkgsProblem::NonSyntacticCallPackage { package_name, file, line, column, definition } =>
-                write!(
+            NixpkgsProblem::NonSyntacticCallPackage { package_name, file, line, column, definition } => {
+                // This is needed such multi-line definitions don't look odd
+                // A bit round-about, but it works and we might not need anything more complicated
+                let definition_indented =
+                    // The entire code should be indented 4 spaces
+                    textwrap::indent(
+                        // But first we want to strip the code's natural indentation
+                        &textwrap::dedent(
+                            // The definition _doesn't_ include the leading spaces, but we can
+                            // recover those from the column
+                            &format!("{}{definition}",
+                            " ".repeat(column - 1)),
+                        ),
+                        "    ",
+                    );
+                writedoc!(
                     f,
-                    "Because {} exists, the attribute `pkgs.{package_name}` must be defined as `callPackage {} {{ ... }}`. This is however not the case: The attribute is defined in {}:{}:{} as\n\t{}",
+                    "
+                    - Because {} exists, the attribute `pkgs.{package_name}` must be defined like
+
+                        {package_name} = callPackage {} {{ /* ... */ }};
+
+                      This is however not the case.
+                      It is defined in {}:{} as
+
+                    {}",
                     structure::relative_dir_for_package(package_name).display(),
                     structure::relative_file_for_package(package_name).display(),
                     file.display(),
                     line,
-                    column,
-                    definition,
-                ),
+                    definition_indented,
+                )
+            }
             NixpkgsProblem::NonDerivation { relative_package_file, package_name } =>
                 write!(
                     f,
diff --git a/pkgs/test/nixpkgs-check-by-name/tests/non-syntactical-callPackage-by-name/expected b/pkgs/test/nixpkgs-check-by-name/tests/non-syntactical-callPackage-by-name/expected
index f590ef4ff9fa..e62009633885 100644
--- a/pkgs/test/nixpkgs-check-by-name/tests/non-syntactical-callPackage-by-name/expected
+++ b/pkgs/test/nixpkgs-check-by-name/tests/non-syntactical-callPackage-by-name/expected
@@ -1,2 +1,8 @@
-Because pkgs/by-name/fo/foo exists, the attribute `pkgs.foo` must be defined as `callPackage pkgs/by-name/fo/foo/package.nix { ... }`. This is however not the case: The attribute is defined in all-packages.nix:4:3 as
-	foo = self.bar;
+- Because pkgs/by-name/fo/foo exists, the attribute `pkgs.foo` must be defined like
+
+    foo = callPackage pkgs/by-name/fo/foo/package.nix { /* ... */ };
+
+  This is however not the case.
+  It is defined in all-packages.nix:4 as
+
+    foo = self.bar;
diff --git a/pkgs/test/nixpkgs-check-by-name/tests/override-different-file/expected b/pkgs/test/nixpkgs-check-by-name/tests/override-different-file/expected
index 3566b15bdbc4..18bf137364fe 100644
--- a/pkgs/test/nixpkgs-check-by-name/tests/override-different-file/expected
+++ b/pkgs/test/nixpkgs-check-by-name/tests/override-different-file/expected
@@ -1,8 +1,8 @@
 - Because pkgs/by-name/no/nonDerivation exists, the attribute `pkgs.nonDerivation` must be defined like
 
-    nonDerivation = callPackage ./pkgs/by-name/no/nonDerivation/package.nix { /* ... */ }
+    nonDerivation = callPackage ./pkgs/by-name/no/nonDerivation/package.nix { /* ... */ };
 
   This is however not the case: The first `callPackage` argument is the wrong path.
   It is defined in all-packages.nix:2:3 as
 
-    nonDerivation = callPackage ./someDrv.nix { /* ... */ }
+    nonDerivation = callPackage ./someDrv.nix { /* ... */ };
diff --git a/pkgs/test/nixpkgs-check-by-name/tests/override-no-call-package/expected b/pkgs/test/nixpkgs-check-by-name/tests/override-no-call-package/expected
index 25fc867b04fe..e31f9eb6d539 100644
--- a/pkgs/test/nixpkgs-check-by-name/tests/override-no-call-package/expected
+++ b/pkgs/test/nixpkgs-check-by-name/tests/override-no-call-package/expected
@@ -1,2 +1,8 @@
-Because pkgs/by-name/no/nonDerivation exists, the attribute `pkgs.nonDerivation` must be defined as `callPackage pkgs/by-name/no/nonDerivation/package.nix { ... }`. This is however not the case: The attribute is defined in all-packages.nix:2:3 as
-	nonDerivation = self.someDrv;
+- Because pkgs/by-name/no/nonDerivation exists, the attribute `pkgs.nonDerivation` must be defined like
+
+    nonDerivation = callPackage pkgs/by-name/no/nonDerivation/package.nix { /* ... */ };
+
+  This is however not the case.
+  It is defined in all-packages.nix:2 as
+
+    nonDerivation = self.someDrv;