diff --git a/aclocal.m4 b/aclocal.m4
index c7b94fed7501..154aab82c100 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -49,6 +49,14 @@ AC_DEFUN([OCAML_CC_VENDOR], [
 msvc _MSC_VER
 #elif defined(__INTEL_COMPILER)
 icc __INTEL_COMPILER
+#elif defined(__MINGW32__)
+#include <_mingw_mac.h>
+mingw32 __MINGW64_VERSION_MAJOR __MINGW64_VERSION_MINOR
+# if defined(__clang_major__) && defined(__clang_minor__)
+  clang __clang_major__ __clang_minor__
+# elif defined(__GNUC__) && defined(__GNUC_MINOR__)
+  gcc __GNUC__ __GNUC_MINOR__
+# endif
 #elif defined(__clang_major__) && defined(__clang_minor__)
 clang __clang_major__ __clang_minor__
 #elif defined(__GNUC__) && defined(__GNUC_MINOR__)
@@ -62,8 +70,8 @@ unknown
 #endif]
     )],
     [AC_CACHE_VAL([ocaml_cv_cc_vendor],
-      [ocaml_cv_cc_vendor=`grep ['^[a-z]'] conftest.i | tr -s ' ' '-' \
-                                                      | tr -d '\r'`])],
+      [ocaml_cv_cc_vendor=`sed -e '/^#/d' conftest.i | tr -s '[:space:]' '-' \
+                             | sed -e 's/^-//' -e 's/-$//'`])],
     [AC_MSG_FAILURE([unexpected preprocessor failure])])
   AC_MSG_RESULT([$ocaml_cv_cc_vendor])
 ])
diff --git a/configure b/configure
index 0c7f22b37eee..21ac408feeed 100755
--- a/configure
+++ b/configure
@@ -13542,6 +13542,14 @@ printf %s "checking C compiler vendor... " >&6; }
 msvc _MSC_VER
 #elif defined(__INTEL_COMPILER)
 icc __INTEL_COMPILER
+#elif defined(__MINGW32__)
+#include <_mingw_mac.h>
+mingw32 __MINGW64_VERSION_MAJOR __MINGW64_VERSION_MINOR
+# if defined(__clang_major__) && defined(__clang_minor__)
+  clang __clang_major__ __clang_minor__
+# elif defined(__GNUC__) && defined(__GNUC_MINOR__)
+  gcc __GNUC__ __GNUC_MINOR__
+# endif
 #elif defined(__clang_major__) && defined(__clang_minor__)
 clang __clang_major__ __clang_minor__
 #elif defined(__GNUC__) && defined(__GNUC_MINOR__)
@@ -13561,8 +13569,8 @@ then :
 then :
   printf %s "(cached) " >&6
 else $as_nop
-  ocaml_cv_cc_vendor=`grep '^[a-z]' conftest.i | tr -s ' ' '-' \
-                                                      | tr -d '\r'`
+  ocaml_cv_cc_vendor=`sed -e '/^#/d' conftest.i | tr -s '[:space:]' '-' \
+                             | sed -e 's/^-//' -e 's/-$//'`
 fi
 
 else $as_nop
@@ -13861,44 +13869,31 @@ esac
 # Concerning optimization level, -O3 is somewhat risky, so take -O2.
 # Concerning language version, recent enough versions of GCC and Clang
 # default to gnu11 (C11 + GNU extensions) or gnu17, which is fine.
-
-# Note: the vendor macro can not recognize MinGW because it calls the
-# C preprocessor directly so no compiler specific macro like __MING32__
-# is defined. We thus catch MinGW first by looking at host and examine
-# the vendor only as a fall-back. We could put tis part of the logic
-# in the macro itself, too
-case $host in #(
-  *-*-mingw32*) :
-    case $ocaml_cv_cc_vendor in #(
-  gcc-[01234]-*) :
-    as_fn_error $? "This version of MinGW-w64 GCC is too old. Please use GCC version 5 or above." "$LINENO" 5 ;; #(
-  gcc-*) :
-    internal_cflags="-Wno-unused $cc_warnings \
--fexcess-precision=standard"
-        # TODO: see whether the code can be fixed to avoid -Wno-unused
-        common_cflags="-O2 -fno-strict-aliasing -fwrapv -mms-bitfields"
-        internal_cppflags='-D__USE_MINGW_ANSI_STDIO=0 -DUNICODE -D_UNICODE'
-        internal_cppflags="$internal_cppflags -DWINDOWS_UNICODE="
-        internal_cppflags="${internal_cppflags}\$(WINDOWS_UNICODE)" ;; #(
-  *) :
-    as_fn_error $? "Unsupported C compiler for a MinGW-w64 build" "$LINENO" 5 ;;
-esac ;; #(
-  *) :
-    case $ocaml_cv_cc_vendor in #(
+case $ocaml_cv_cc_vendor in #(
   clang-*) :
     common_cflags="-O2 -fno-strict-aliasing -fwrapv";
-      internal_cflags="$cc_warnings -fno-common" ;; #(
-  gcc-[0123]-*|gcc-4-[0-8]) :
+    internal_cflags="$cc_warnings -fno-common" ;; #(
+  *gcc-[0123]-*|*gcc-4-[0-8]) :
     # No C11 support
-      as_fn_error 69 "This version of GCC is too old. Please use GCC version 4.9 or above." "$LINENO" 5 ;; #(
+    as_fn_error 69 "This version of GCC is too old. Please use GCC version 4.9 or above." "$LINENO" 5 ;; #(
   gcc-*) :
     common_cflags="-O2 -fno-strict-aliasing -fwrapv";
-      internal_cflags="$cc_warnings -fno-common -fexcess-precision=standard \
+    internal_cflags="$cc_warnings -fno-common -fexcess-precision=standard \
 -Wvla" ;; #(
+  mingw32-*-*-gcc-*|mingw32-*-*-clang-*) :
+    internal_cflags="-Wno-unused $cc_warnings \
+-fexcess-precision=standard"
+    # TODO: see whether the code can be fixed to avoid -Wno-unused
+    common_cflags="-O2 -fno-strict-aliasing -fwrapv -mms-bitfields"
+    internal_cppflags='-D__USE_MINGW_ANSI_STDIO=0 -DUNICODE -D_UNICODE'
+    internal_cppflags="$internal_cppflags -DWINDOWS_UNICODE="
+    internal_cppflags="${internal_cppflags}\$(WINDOWS_UNICODE)" ;; #(
+  mingw32-*) :
+    as_fn_error $? "Unsupported C compiler for a MinGW-w64 build" "$LINENO" 5 ;; #(
   msvc-*) :
     common_cflags="-nologo -O2 -Gy- -MD $cc_warnings"
-      common_cppflags="-D_CRT_SECURE_NO_DEPRECATE"
-      internal_cppflags='-DUNICODE -D_UNICODE'
+    common_cppflags="-D_CRT_SECURE_NO_DEPRECATE"
+    internal_cppflags='-DUNICODE -D_UNICODE'
 
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether the C compiler supports -d2VolatileMetadata-" >&5
 printf %s "checking whether the C compiler supports -d2VolatileMetadata-... " >&6; }
@@ -13921,23 +13916,22 @@ fi
 rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
   CFLAGS="$saved_CFLAGS"
 
-      if test "x$cl_has_volatile_metadata" = "xtrue"
+    if test "x$cl_has_volatile_metadata" = "xtrue"
 then :
   internal_cflags='-d2VolatileMetadata-'
 fi
-      internal_cppflags="$internal_cppflags -DWINDOWS_UNICODE="
-      internal_cppflags="${internal_cppflags}\$(WINDOWS_UNICODE)" ;; #(
+    internal_cppflags="$internal_cppflags -DWINDOWS_UNICODE="
+    internal_cppflags="${internal_cppflags}\$(WINDOWS_UNICODE)" ;; #(
   xlc-*) :
     common_cflags="-O5 -qtune=balanced -qnoipa -qinline";
-      internal_cflags="$cc_warnings" ;; #(
+    internal_cflags="$cc_warnings" ;; #(
   sunc-*) :
     # Optimization should be >= O4 to inline functions
-              # and prevent unresolved externals
-      common_cflags="-O4 -xc99=all -D_XPG6 $CFLAGS";
-      internal_cflags="$cc_warnings" ;; #(
+            # and prevent unresolved externals
+    common_cflags="-O4 -xc99=all -D_XPG6 $CFLAGS";
+    internal_cflags="$cc_warnings" ;; #(
   *) :
     common_cflags="-O" ;;
-esac ;;
 esac
 
 # Enable SSE2 on x86 mingw to avoid using 80-bit registers.
diff --git a/configure.ac b/configure.ac
index 28ad57a2933c..f2dd9c510ab9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -788,56 +788,45 @@ AS_CASE([$enable_warn_error,OCAML__DEVELOPMENT_VERSION],
 # Concerning optimization level, -O3 is somewhat risky, so take -O2.
 # Concerning language version, recent enough versions of GCC and Clang
 # default to gnu11 (C11 + GNU extensions) or gnu17, which is fine.
-
-# Note: the vendor macro can not recognize MinGW because it calls the
-# C preprocessor directly so no compiler specific macro like __MING32__
-# is defined. We thus catch MinGW first by looking at host and examine
-# the vendor only as a fall-back. We could put tis part of the logic
-# in the macro itself, too
-AS_CASE([$host],
-  [*-*-mingw32*],
-    [AS_CASE([$ocaml_cv_cc_vendor],
-      [gcc-[[01234]]-*],
-        [AC_MSG_ERROR(m4_normalize([This version of MinGW-w64 GCC is too old.
-          Please use GCC version 5 or above.]))],
-      [gcc-*],
-        [internal_cflags="-Wno-unused $cc_warnings \
--fexcess-precision=standard"
-        # TODO: see whether the code can be fixed to avoid -Wno-unused
-        common_cflags="-O2 -fno-strict-aliasing -fwrapv -mms-bitfields"
-        internal_cppflags='-D__USE_MINGW_ANSI_STDIO=0 -DUNICODE -D_UNICODE'
-        internal_cppflags="$internal_cppflags -DWINDOWS_UNICODE="
-        internal_cppflags="${internal_cppflags}\$(WINDOWS_UNICODE)"],
-      [AC_MSG_ERROR([Unsupported C compiler for a MinGW-w64 build])])],
-  [AS_CASE([$ocaml_cv_cc_vendor],
-    [clang-*],
-      [common_cflags="-O2 -fno-strict-aliasing -fwrapv";
-      internal_cflags="$cc_warnings -fno-common"],
-    [gcc-[[0123]]-*|gcc-4-[[0-8]]],
-      # No C11 support
-      [AC_MSG_ERROR(m4_normalize([This version of GCC is too old.
-        Please use GCC version 4.9 or above.]), 69)],
-    [gcc-*],
-      [common_cflags="-O2 -fno-strict-aliasing -fwrapv";
-      internal_cflags="$cc_warnings -fno-common -fexcess-precision=standard \
+AS_CASE([$ocaml_cv_cc_vendor],
+  [clang-*],
+    [common_cflags="-O2 -fno-strict-aliasing -fwrapv";
+    internal_cflags="$cc_warnings -fno-common"],
+  [*gcc-[[0123]]-*|*gcc-4-[[0-8]]],
+    # No C11 support
+    [AC_MSG_ERROR(m4_normalize([This version of GCC is too old.
+      Please use GCC version 4.9 or above.]), 69)],
+  [gcc-*],
+    [common_cflags="-O2 -fno-strict-aliasing -fwrapv";
+    internal_cflags="$cc_warnings -fno-common -fexcess-precision=standard \
 -Wvla"],
-    [msvc-*],
-      [common_cflags="-nologo -O2 -Gy- -MD $cc_warnings"
-      common_cppflags="-D_CRT_SECURE_NO_DEPRECATE"
-      internal_cppflags='-DUNICODE -D_UNICODE'
-      OCAML_CL_HAS_VOLATILE_METADATA
-      AS_IF([test "x$cl_has_volatile_metadata" = "xtrue"],
-            [internal_cflags='-d2VolatileMetadata-'])
-      internal_cppflags="$internal_cppflags -DWINDOWS_UNICODE="
-      internal_cppflags="${internal_cppflags}\$(WINDOWS_UNICODE)"],
-    [xlc-*],
-      [common_cflags="-O5 -qtune=balanced -qnoipa -qinline";
-      internal_cflags="$cc_warnings"],
-    [sunc-*], # Optimization should be >= O4 to inline functions
-              # and prevent unresolved externals
-      [common_cflags="-O4 -xc99=all -D_XPG6 $CFLAGS";
-      internal_cflags="$cc_warnings"],
-    [common_cflags="-O"])])
+  [mingw32-*-*-gcc-*|mingw32-*-*-clang-*],
+    [internal_cflags="-Wno-unused $cc_warnings \
+-fexcess-precision=standard"
+    # TODO: see whether the code can be fixed to avoid -Wno-unused
+    common_cflags="-O2 -fno-strict-aliasing -fwrapv -mms-bitfields"
+    internal_cppflags='-D__USE_MINGW_ANSI_STDIO=0 -DUNICODE -D_UNICODE'
+    internal_cppflags="$internal_cppflags -DWINDOWS_UNICODE="
+    internal_cppflags="${internal_cppflags}\$(WINDOWS_UNICODE)"],
+  [mingw32-*],
+    [AC_MSG_ERROR([Unsupported C compiler for a MinGW-w64 build])],
+  [msvc-*],
+    [common_cflags="-nologo -O2 -Gy- -MD $cc_warnings"
+    common_cppflags="-D_CRT_SECURE_NO_DEPRECATE"
+    internal_cppflags='-DUNICODE -D_UNICODE'
+    OCAML_CL_HAS_VOLATILE_METADATA
+    AS_IF([test "x$cl_has_volatile_metadata" = "xtrue"],
+          [internal_cflags='-d2VolatileMetadata-'])
+    internal_cppflags="$internal_cppflags -DWINDOWS_UNICODE="
+    internal_cppflags="${internal_cppflags}\$(WINDOWS_UNICODE)"],
+  [xlc-*],
+    [common_cflags="-O5 -qtune=balanced -qnoipa -qinline";
+    internal_cflags="$cc_warnings"],
+  [sunc-*], # Optimization should be >= O4 to inline functions
+            # and prevent unresolved externals
+    [common_cflags="-O4 -xc99=all -D_XPG6 $CFLAGS";
+    internal_cflags="$cc_warnings"],
+  [common_cflags="-O"])
 
 # Enable SSE2 on x86 mingw to avoid using 80-bit registers.
 AS_CASE([$host],
diff --git a/runtime/caml/fail.h b/runtime/caml/fail.h
index 4652bb896920..91c8cf6973c3 100644
--- a/runtime/caml/fail.h
+++ b/runtime/caml/fail.h
@@ -51,8 +51,13 @@ struct longjmp_buffer {
 struct longjmp_buffer {
   intptr_t buf[5];
 };
+#if defined(__clang__)
+#define sigsetjmp(buf,save) __builtin_setjmp((void **)(buf))
+#define siglongjmp(buf,val) __builtin_longjmp((void **)(buf),val)
+#else
 #define sigsetjmp(buf,save) __builtin_setjmp(buf)
 #define siglongjmp(buf,val) __builtin_longjmp(buf,val)
+#endif
 #else
 struct longjmp_buffer {
   jmp_buf buf;
diff --git a/runtime/runtime_events.c b/runtime/runtime_events.c
index ef95da40b05d..05bbbebc2505 100644
--- a/runtime/runtime_events.c
+++ b/runtime/runtime_events.c
@@ -252,10 +252,11 @@ void caml_runtime_events_destroy(void) {
 static void runtime_events_create_from_stw_single(void) {
   /* Don't initialise runtime_events twice */
   if (!atomic_load_acquire(&runtime_events_enabled)) {
-    int ret, ring_headers_length, ring_data_length;
+    int ring_headers_length, ring_data_length;
 #ifdef _WIN32
     DWORD pid = GetCurrentProcessId();
 #else
+    int ret;
     int ring_fd;
     long int pid = getpid();
 #endif
diff --git a/runtime/win32.c b/runtime/win32.c
index 7f1bcf976877..6b20f14e305d 100644
--- a/runtime/win32.c
+++ b/runtime/win32.c
@@ -361,7 +361,7 @@ static void expand_argument(wchar_t * arg)
 
 static void expand_pattern(wchar_t * pat)
 {
-  wchar_t * prefix, * p, * name;
+  wchar_t * prefix, * name;
   intptr_t handle;
   struct _wfinddata_t ffblk;
   size_t i;
@@ -1094,7 +1094,6 @@ CAMLexport clock_t caml_win32_clock(void)
 {
   FILETIME _creation, _exit;
   CAML_ULONGLONG_FILETIME stime, utime;
-  ULARGE_INTEGER tmp;
   ULONGLONG clocks_per_sec;
 
   if (!(GetProcessTimes(GetCurrentProcess(), &_creation, &_exit,