diff --git a/tests/converters/assimp.test.ts b/tests/converters/assimp.test.ts
index 01ba0ad..c7052fc 100644
--- a/tests/converters/assimp.test.ts
+++ b/tests/converters/assimp.test.ts
@@ -3,6 +3,7 @@ import { convert } from "../../src/converters/assimp.ts";
 import {
   runConvertFailTest,
   runConvertLogsStderror,
+  runConvertLogsStderrorAndStdout,
   runConvertSuccessTest,
 } from "./helpers/converters.ts";
 
@@ -17,3 +18,7 @@ test("convert rejects when execFile fails", async () => {
 test("convert logs stderr when present", async () => {
   await runConvertLogsStderror(convert);
 });
+
+test("convert logs both stderr and stdout when present", async () => {
+  await runConvertLogsStderrorAndStdout(convert);
+});
diff --git a/tests/converters/calibre.test.ts b/tests/converters/calibre.test.ts
index d060097..41fea53 100644
--- a/tests/converters/calibre.test.ts
+++ b/tests/converters/calibre.test.ts
@@ -3,6 +3,7 @@ import { convert } from "../../src/converters/calibre.ts";
 import {
   runConvertFailTest,
   runConvertLogsStderror,
+  runConvertLogsStderrorAndStdout,
   runConvertSuccessTest,
 } from "./helpers/converters.ts";
 
@@ -17,3 +18,7 @@ test("convert rejects when execFile fails", async () => {
 test("convert logs stderr when present", async () => {
   await runConvertLogsStderror(convert);
 });
+
+test("convert logs both stderr and stdout when present", async () => {
+  await runConvertLogsStderrorAndStdout(convert);
+});
diff --git a/tests/converters/dvisvgm.test.ts b/tests/converters/dvisvgm.test.ts
index 2c91a2f..b7211e4 100644
--- a/tests/converters/dvisvgm.test.ts
+++ b/tests/converters/dvisvgm.test.ts
@@ -5,6 +5,7 @@ import { ExecFileFn } from "../../src/converters/types.ts";
 import {
   runConvertFailTest,
   runConvertLogsStderror,
+  runConvertLogsStderrorAndStdout,
   runConvertSuccessTest,
 } from "./helpers/converters.ts";
 
@@ -26,6 +27,10 @@ test("convert logs stderr when present", async () => {
   await runConvertLogsStderror(convert);
 });
 
+test("convert logs both stderr and stdout when present", async () => {
+  await runConvertLogsStderrorAndStdout(convert);
+});
+
 test("convert respects eps filetype", async () => {
   const originalConsoleLog = console.log;
 
diff --git a/tests/converters/graphicsmagick.test.ts b/tests/converters/graphicsmagick.test.ts
index df9bda8..8c038e2 100644
--- a/tests/converters/graphicsmagick.test.ts
+++ b/tests/converters/graphicsmagick.test.ts
@@ -3,6 +3,7 @@ import { convert } from "../../src/converters/graphicsmagick.ts";
 import {
   runConvertFailTest,
   runConvertLogsStderror,
+  runConvertLogsStderrorAndStdout,
   runConvertSuccessTest,
 } from "./helpers/converters.ts";
 
@@ -17,3 +18,7 @@ test("convert rejects when execFile fails", async () => {
 test("convert logs stderr when present", async () => {
   await runConvertLogsStderror(convert);
 });
+
+test("convert logs both stderr and stdout when present", async () => {
+  await runConvertLogsStderrorAndStdout(convert);
+});
diff --git a/tests/converters/helpers/converters.ts b/tests/converters/helpers/converters.ts
index 950c873..02aa084 100644
--- a/tests/converters/helpers/converters.ts
+++ b/tests/converters/helpers/converters.ts
@@ -65,3 +65,34 @@ export async function runConvertLogsStderror(convertFn: ConvertFnWithExecFile) {
 
   expect(loggedMessage).toBe("stderr: Fake stderr");
 }
+
+export async function runConvertLogsStderrorAndStdout(convertFn: ConvertFnWithExecFile) {
+  const originalConsoleError = console.error;
+  const originalConsoleLog = console.log;
+
+  let loggedError = "";
+  let loggedMessage = "";
+  console.error = (msg) => {
+    loggedError = msg;
+  };
+  console.log = (msg) => {
+    loggedMessage = msg;
+  };
+
+  const mockExecFile = (
+    _cmd: string,
+    _args: string[],
+    options: unknown,
+    callback: (err: Error | null, stdout: string, stderr: string) => void,
+  ) => {
+    callback(null, "Fake stdout", "Fake stderr");
+  };
+
+  await convertFn("file.obj", "obj", "stl", "out.stl", undefined, mockExecFile);
+
+  console.error = originalConsoleError;
+  console.log = originalConsoleLog;
+
+  expect(loggedError).toBe("stderr: Fake stderr");
+  expect(loggedMessage).toBe("stdout: Fake stdout");
+}
diff --git a/tests/converters/imagemagick.test.ts b/tests/converters/imagemagick.test.ts
index 06f1d13..de2467c 100644
--- a/tests/converters/imagemagick.test.ts
+++ b/tests/converters/imagemagick.test.ts
@@ -5,6 +5,7 @@ import { ExecFileFn } from "../../src/converters/types.ts";
 import {
   runConvertFailTest,
   runConvertLogsStderror,
+  runConvertLogsStderrorAndStdout,
   runConvertSuccessTest,
 } from "./helpers/converters.ts";
 
@@ -26,6 +27,10 @@ test("convert logs stderr when present", async () => {
   await runConvertLogsStderror(convert);
 });
 
+test("convert logs both stderr and stdout when present", async () => {
+  await runConvertLogsStderrorAndStdout(convert);
+});
+
 test("convert respects ico conversion target type", async () => {
   const originalConsoleLog = console.log;
 
diff --git a/tests/converters/inkscape.test.ts b/tests/converters/inkscape.test.ts
index 39d21c3..f61746e 100644
--- a/tests/converters/inkscape.test.ts
+++ b/tests/converters/inkscape.test.ts
@@ -3,6 +3,7 @@ import { convert } from "../../src/converters/inkscape.ts";
 import {
   runConvertFailTest,
   runConvertLogsStderror,
+  runConvertLogsStderrorAndStdout,
   runConvertSuccessTest,
 } from "./helpers/converters.ts";
 
@@ -17,3 +18,7 @@ test("convert rejects when execFile fails", async () => {
 test("convert logs stderr when present", async () => {
   await runConvertLogsStderror(convert);
 });
+
+test("convert logs both stderr and stdout when present", async () => {
+  await runConvertLogsStderrorAndStdout(convert);
+});
diff --git a/tests/converters/libheif.test.ts b/tests/converters/libheif.test.ts
index 33625c5..267734d 100644
--- a/tests/converters/libheif.test.ts
+++ b/tests/converters/libheif.test.ts
@@ -3,6 +3,7 @@ import { convert } from "../../src/converters/libheif.ts";
 import {
   runConvertFailTest,
   runConvertLogsStderror,
+  runConvertLogsStderrorAndStdout,
   runConvertSuccessTest,
 } from "./helpers/converters.ts";
 
@@ -17,3 +18,7 @@ test("convert rejects when execFile fails", async () => {
 test("convert logs stderr when present", async () => {
   await runConvertLogsStderror(convert);
 });
+
+test("convert logs both stderr and stdout when present", async () => {
+  await runConvertLogsStderrorAndStdout(convert);
+});
diff --git a/tests/converters/libjxl.test.ts b/tests/converters/libjxl.test.ts
index ed352d6..e96c5f8 100644
--- a/tests/converters/libjxl.test.ts
+++ b/tests/converters/libjxl.test.ts
@@ -5,6 +5,7 @@ import { ExecFileFn } from "../../src/converters/types.ts";
 import {
   runConvertFailTest,
   runConvertLogsStderror,
+  runConvertLogsStderrorAndStdout,
   runConvertSuccessTest,
 } from "./helpers/converters.ts";
 
@@ -26,6 +27,10 @@ test("convert logs stderr when present", async () => {
   await runConvertLogsStderror(convert);
 });
 
+test("convert logs both stderr and stdout when present", async () => {
+  await runConvertLogsStderrorAndStdout(convert);
+});
+
 test("convert uses djxl with input filetype being jxl", async () => {
   const originalConsoleLog = console.log;
 
diff --git a/tests/converters/potrace.test.ts b/tests/converters/potrace.test.ts
index 5f37450..f1852a7 100644
--- a/tests/converters/potrace.test.ts
+++ b/tests/converters/potrace.test.ts
@@ -3,6 +3,7 @@ import { convert } from "../../src/converters/potrace.ts";
 import {
   runConvertFailTest,
   runConvertLogsStderror,
+  runConvertLogsStderrorAndStdout,
   runConvertSuccessTest,
 } from "./helpers/converters.ts";
 
@@ -17,3 +18,7 @@ test("convert rejects when execFile fails", async () => {
 test("convert logs stderr when present", async () => {
   await runConvertLogsStderror(convert);
 });
+
+test("convert logs both stderr and stdout when present", async () => {
+  await runConvertLogsStderrorAndStdout(convert);
+});
diff --git a/tests/converters/resvg.test.ts b/tests/converters/resvg.test.ts
index d2eae2f..cdcb6b9 100644
--- a/tests/converters/resvg.test.ts
+++ b/tests/converters/resvg.test.ts
@@ -3,6 +3,7 @@ import { convert } from "../../src/converters/resvg.ts";
 import {
   runConvertFailTest,
   runConvertLogsStderror,
+  runConvertLogsStderrorAndStdout,
   runConvertSuccessTest,
 } from "./helpers/converters.ts";
 
@@ -17,3 +18,7 @@ test("convert rejects when execFile fails", async () => {
 test("convert logs stderr when present", async () => {
   await runConvertLogsStderror(convert);
 });
+
+test("convert logs both stderr and stdout when present", async () => {
+  await runConvertLogsStderrorAndStdout(convert);
+});
diff --git a/tests/converters/vips.test.ts b/tests/converters/vips.test.ts
index d7ea9d8..2aa2181 100644
--- a/tests/converters/vips.test.ts
+++ b/tests/converters/vips.test.ts
@@ -5,6 +5,7 @@ import { convert } from "../../src/converters/vips.ts";
 import {
   runConvertFailTest,
   runConvertLogsStderror,
+  runConvertLogsStderrorAndStdout,
   runConvertSuccessTest,
 } from "./helpers/converters.ts";
 
@@ -26,6 +27,10 @@ test("convert logs stderr when present", async () => {
   await runConvertLogsStderror(convert);
 });
 
+test("convert logs both stderr and stdout when present", async () => {
+  await runConvertLogsStderrorAndStdout(convert);
+});
+
 test("convert uses action pdfload with filetype being pdf", async () => {
   const originalConsoleLog = console.log;
 
diff --git a/tests/converters/xelatex.test.ts b/tests/converters/xelatex.test.ts
index 5d81d09..5794b70 100644
--- a/tests/converters/xelatex.test.ts
+++ b/tests/converters/xelatex.test.ts
@@ -3,6 +3,7 @@ import { convert } from "../../src/converters/xelatex.ts";
 import {
   runConvertFailTest,
   runConvertLogsStderror,
+  runConvertLogsStderrorAndStdout,
   runConvertSuccessTest,
 } from "./helpers/converters.ts";
 
@@ -17,3 +18,7 @@ test("convert rejects when execFile fails", async () => {
 test("convert logs stderr when present", async () => {
   await runConvertLogsStderror(convert);
 });
+
+test("convert logs both stderr and stdout when present", async () => {
+  await runConvertLogsStderrorAndStdout(convert);
+});