diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 6af89d9..cd64e0f 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -3,8 +3,8 @@ name: C/C++ CI
 on: [pull_request]
 
 jobs:
-  build:
 
+  linux64-gui:
     runs-on: ubuntu-latest
 
     steps:
@@ -14,8 +14,80 @@ jobs:
     - name: configure
       run: ./configure
     - name: make
-      run: make
+      run: nproc && make -j$(nproc)
     - name: check executability
       run: ./dvdisaster --version
+    - name: check executable
+      run: file dvdisaster && file dvdisaster | grep -q 'ELF 64'
+    - name: regression tests
+      run: mkdir /var/tmp/regtest && ./regtest/runtests.sh
+
+  linux64-cli:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: install prerequisites
+      run: sudo apt update && sudo apt install -y libglib2.0-dev
+    - name: configure
+      run: env CLI_ONLY=1 ./configure
+    - name: make
+      run: nproc && make -j$(nproc)
+    - name: check executability
+      run: ./dvdisaster --version
+    - name: check executable
+      run: file dvdisaster && file dvdisaster | grep -q 'ELF 64'
+    - name: regression tests
+      run: mkdir /var/tmp/regtest && ./regtest/runtests.sh
+
+  win64:
+    runs-on: windows-2016
+
+    defaults:
+      run:
+        shell: msys2 {0}
+    steps:
+    - uses: msys2/setup-msys2@v2
+      with:
+        msystem: MINGW64
+        update: false
+        install: git diffutils make pkg-config mingw-w64-x86_64-gtk2 mingw-w64-x86_64-glib2 mingw-w64-x86_64-gcc
+    - run: git config --global core.autocrlf input
+      shell: bash
+    - uses: actions/checkout@v2
+    - name: configure
+      run: ./configure
+    - name: make
+      run: nproc && make -j$(nproc)
+    - name: check executability
+      run: ./dvdisaster.exe --version
+    - name: check executable
+      run: file dvdisaster.exe && file dvdisaster.exe | grep -q 'x86-64, for MS Windows'
+    - name: regression tests
+      run: mkdir /var/tmp/regtest && ./regtest/runtests.sh
+
+  win32:
+    runs-on: windows-2016
+
+    defaults:
+      run:
+        shell: msys2 {0}
+    steps:
+    - uses: msys2/setup-msys2@v2
+      with:
+        msystem: MINGW32
+        update: false
+        install: git diffutils make pkg-config mingw-w64-i686-gtk2 mingw-w64-i686-glib2 mingw-w64-i686-gcc
+    - run: git config --global core.autocrlf input
+      shell: bash
+    - uses: actions/checkout@v2
+    - name: configure
+      run: ./configure
+    - name: make
+      run: nproc && make -j$(nproc)
+    - name: check executability
+      run: ./dvdisaster.exe --version
+    - name: check executable
+      run: file dvdisaster.exe && file dvdisaster.exe | grep -q '386, for MS Windows'
     - name: regression tests
       run: mkdir /var/tmp/regtest && ./regtest/runtests.sh
diff --git a/large-io.c b/large-io.c
index 01fbb02..b3aa295 100644
--- a/large-io.c
+++ b/large-io.c
@@ -40,8 +40,8 @@
 
 #include <windows.h>
 
-#define stat _stati64
-#define lseek _lseeki64
+#define large_stat _stati64
+#define large_lseek _lseeki64
 
 /* The original windows ftruncate has off_size (32bit) */
 
@@ -62,6 +62,8 @@ int large_ftruncate(int fd, gint64 size)
 
 #else
   #define large_ftruncate ftruncate
+  #define large_stat stat
+  #define large_lseek lseek
 #endif /* SYS_MINGW */
 
 /*
@@ -90,7 +92,7 @@ int LargeStat(char *path, guint64 *length_return)
 
    if(!cp_path) return FALSE;
 
-   if(stat(cp_path, &mystat) == -1)
+   if(large_stat(cp_path, &mystat) == -1)
    {  g_free(cp_path);
       return FALSE;
    }
@@ -113,7 +115,7 @@ int DirStat(char *path)
 
    if(!cp_path) return FALSE;
 
-   if(stat(cp_path, &mystat) == -1)
+   if(large_stat(cp_path, &mystat) == -1)
    {  g_free(cp_path);
       return FALSE;
    }
@@ -148,7 +150,7 @@ LargeFile* LargeOpen(char *name, int flags, mode_t mode)
 
    /* Do not try to open directories etc. */
 
-   if(    (stat(cp_path, &mystat) == 0)
+   if(    (large_stat(cp_path, &mystat) == 0)
        && !S_ISREG(mystat.st_mode))
    {  g_free(cp_path), g_free(lf); return NULL;
    }
@@ -175,7 +177,7 @@ LargeFile* LargeOpen(char *name, int flags, mode_t mode)
 int LargeSeek(LargeFile *lf, off_t pos)
 {  
    lf->offset = pos;
-   if(lseek(lf->fileHandle, pos, SEEK_SET) != pos)
+   if(large_lseek(lf->fileHandle, pos, SEEK_SET) != pos)
       return FALSE;
 
    return TRUE;
diff --git a/memtrack.c b/memtrack.c
index 451c9d4..41281b2 100644
--- a/memtrack.c
+++ b/memtrack.c
@@ -20,7 +20,7 @@
  *  along with dvdisaster. If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef SYS_MINGW /* completely untested under Windows, and we don't need it for releases anyway */
+#ifdef WITH_MEMDEBUG_YES
 
 #define _GNU_SOURCE