diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index e1e59247..64393fe6 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -197,6 +197,8 @@ jobs:
             make
             ${{ matrix.env }}${{ matrix.toolchain || 'toolchain' }}
             ${{ matrix.env }}cmake
+            unzip
+            xxhash
       - name: CMake Configure
         shell: msys2 {0}
         run: >
@@ -212,6 +214,9 @@ jobs:
       - name: CTest
         shell: msys2 {0}
         run: ctest --no-tests=error --test-dir out -VV --build-config Release
+      - name: Issue 137 repro
+        shell: msys2 {0}
+        run: ./test/ci/issue137.sh
 
   msys2-makefile-test:
     name: msys2-makefile-${{ matrix.msystem }}
diff --git a/test/ci/issue137.sh b/test/ci/issue137.sh
new file mode 100755
index 00000000..c50e1245
--- /dev/null
+++ b/test/ci/issue137.sh
@@ -0,0 +1,21 @@
+#!/bin/bash
+set -xev
+
+wget https://github.com/aklomp/base64/files/14074869/in.bin.zip
+unzip in.bin.zip
+
+out/bin/base64 in.bin > in.bin.b64
+out/bin/base64 -d in.bin.b64 > out.bin
+
+xxhsum *.bin
+
+# ---
+
+base64 in.bin > in.bin.b64
+out/bin/base64 -d in.bin.b64 > out.bin
+xxhsum *.bin
+
+# ---
+
+base64 -d in.bin.b64 > out.bin
+xxhsum *.bin