diff --git a/.github/workflows/testsuite.yml b/.github/workflows/testsuite.yml
index 3cd0e3e..08905a2 100644
--- a/.github/workflows/testsuite.yml
+++ b/.github/workflows/testsuite.yml
@@ -19,10 +19,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - run: perl -V
       - name: install dependencies
-        uses: perl-actions/install-with-cpm@v1
+        uses: perl-actions/install-with-cpm@stable
         with:
           cpanfile: "cpanfile"
       - name: Makefile.PL
@@ -35,9 +35,7 @@ jobs:
     needs: [ubuntu]
     env:
       PERL_USE_UNSAFE_INC: 0
-      AUTHOR_TESTING: 1
       AUTOMATED_TESTING: 1
-      RELEASE_TESTING: 1
 
     runs-on: ubuntu-latest
 
@@ -46,6 +44,10 @@ jobs:
       matrix:
         perl-version:
           [
+            "5.40",
+            "5.38",
+            "5.36",
+            "5.34",
             "5.32",
             "5.30",
             "5.28",
@@ -58,22 +60,19 @@ jobs:
             "5.14",
             "5.12",
             "5.10",
-            "5.8",
           ]
 
-    container:
-      image: perl:${{ matrix.perl-version }}
-
     steps:
-      - uses: actions/checkout@v2
-      - run: perl -V
-      - name: install dependencies
-        uses: perl-actions/install-with-cpm@v1
+      - uses: actions/checkout@v4
+      - name: Set up perl ${{ matrix.perl-version }}
+        uses: shogo82148/actions-setup-perl@v1
         with:
-          sudo: false
-          cpanfile: "cpanfile"
+          perl-version: ${{ matrix.perl-version }}
+      - run: perl -V
       - name: Makefile.PL
         run: perl -I$(pwd) Makefile.PL
+      - name: make
+        run: make
       - name: make test
         run: make test
 
@@ -81,25 +80,40 @@ jobs:
     needs: [ubuntu]
     env:
       PERL_USE_UNSAFE_INC: 0
-      AUTHOR_TESTING: 1
       AUTOMATED_TESTING: 1
-      RELEASE_TESTING: 1
 
     runs-on: macOS-latest
 
-    strategy:
-      fail-fast: false
-      matrix:
-        perl-version: [latest]
-
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - run: perl -V
       - name: install dependencies
-        uses: perl-actions/install-with-cpm@v1
+        uses: perl-actions/install-with-cpm@stable
         with:
           cpanfile: "cpanfile"
       - name: Makefile.PL
         run: perl -I$(pwd) Makefile.PL
       - name: make test
         run: make test
+
+  windows:
+    needs: [ubuntu]
+    env:
+      PERL_USE_UNSAFE_INC: 0
+      AUTOMATED_TESTING: 1
+
+    runs-on: windows-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Strawberry Perl
+        uses: shogo82148/actions-setup-perl@v1
+        with:
+          perl-version: "5.38"
+      - run: perl -V
+      - name: Makefile.PL
+        run: perl Makefile.PL
+      - name: make
+        run: gmake
+      - name: make test
+        run: gmake test
diff --git a/MD5.xs b/MD5.xs
index 581b0e6..4427add 100644
--- a/MD5.xs
+++ b/MD5.xs
@@ -633,16 +633,17 @@ addfile(self, fh)
     PREINIT:
 	MD5_CTX* context = get_md5_ctx(aTHX_ self);
 	STRLEN fill = context->bytes_low & 0x3F;
+#define BUFFER_SIZE 4096
 #ifdef USE_HEAP_INSTEAD_OF_STACK
 	unsigned char* buffer;
 #else
-	unsigned char buffer[4096];
+	unsigned char buffer[BUFFER_SIZE];
 #endif
 	int  n;
     CODE:
 	if (fh) {
 #ifdef USE_HEAP_INSTEAD_OF_STACK
-	    New(0, buffer, 4096, unsigned char);
+	    New(0, buffer, BUFFER_SIZE, unsigned char);
 	    assert(buffer);
 #endif
             if (fill) {
@@ -658,7 +659,7 @@ addfile(self, fh)
 	    }
 
 	    /* Process blocks until EOF or error */
-            while ( (n = PerlIO_read(fh, buffer, sizeof(buffer))) > 0) {
+            while ( (n = PerlIO_read(fh, buffer, BUFFER_SIZE)) > 0) {
 	        MD5Update(context, buffer, n);
 	    }
 #ifdef USE_HEAP_INSTEAD_OF_STACK
@@ -699,10 +700,10 @@ context(ctx, ...)
 	    STRLEN len;
 	    unsigned long blocks = SvUV(ST(1));
 	    unsigned char *buf = (unsigned char *)(SvPV(ST(2), len));
-	    ctx->A = buf[ 0] | (buf[ 1]<<8) | (buf[ 2]<<16) | (buf[ 3]<<24);
-	    ctx->B = buf[ 4] | (buf[ 5]<<8) | (buf[ 6]<<16) | (buf[ 7]<<24);
-	    ctx->C = buf[ 8] | (buf[ 9]<<8) | (buf[10]<<16) | (buf[11]<<24);
-	    ctx->D = buf[12] | (buf[13]<<8) | (buf[14]<<16) | (buf[15]<<24);
+	    ctx->A = (U32)buf[ 0] | ((U32)buf[ 1]<<8) | ((U32)buf[ 2]<<16) | ((U32)buf[ 3]<<24);
+	    ctx->B = (U32)buf[ 4] | ((U32)buf[ 5]<<8) | ((U32)buf[ 6]<<16) | ((U32)buf[ 7]<<24);
+	    ctx->C = (U32)buf[ 8] | ((U32)buf[ 9]<<8) | ((U32)buf[10]<<16) | ((U32)buf[11]<<24);
+	    ctx->D = (U32)buf[12] | ((U32)buf[13]<<8) | ((U32)buf[14]<<16) | ((U32)buf[15]<<24);
 	    ctx->bytes_low = blocks << 6;
 	    ctx->bytes_high = blocks >> 26;
 	    if (items == 4) {
diff --git a/t/files.t b/t/files.t
index 7d2bc0b..88788e3 100644
--- a/t/files.t
+++ b/t/files.t
@@ -22,7 +22,7 @@ EOT
     # This is the output of: 'md5sum README MD5.xs rfc1321.txt'
     $EXPECT = <<EOT;
 2f93400875dbb56f36691d5f69f3eba5  README
-f4b5da4e0f19b4c0ab374b7085ed8955  MD5.xs
+a141e2845a675e3e7a00f24f071e84cf  MD5.xs
 754b9db19f79dbc4992f7166eb0f37ce  rfc1321.txt
 EOT
 }