diff --git a/CMakeLists.txt b/CMakeLists.txt
index 15f5c945d..6281d9ca3 100755
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.0)
+cmake_minimum_required(VERSION 3.12)
 project(cmark-gfm)
 
 set(PROJECT_VERSION_MAJOR 0)
@@ -20,6 +20,17 @@ option(CMARK_SHARED "Build shared libcmark-gfm library" ON)
 option(CMARK_LIB_FUZZER "Build libFuzzer fuzzing harness" OFF)
 option(CMARK_THREADING "Add locks around static accesses" OFF)
 
+# set a required C standard so we can load stdbool.h
+if(MSVC)
+  set(CMAKE_C_STANDARD 11)
+else()
+  set(CMAKE_C_STANDARD 99)
+endif()
+set(CMAKE_C_STANDARD_REQUIRED YES)
+
+# Use CMake's generated headers instead of the Swift package prebuilt ones
+add_compile_definitions(CMARK_USE_CMAKE_HEADERS)
+
 add_subdirectory(src)
 add_subdirectory(extensions)
 if(CMARK_TESTS AND (CMARK_SHARED OR CMARK_STATIC))
diff --git a/api_test/CMakeLists.txt b/api_test/CMakeLists.txt
index 2ae27d762..151192d8a 100644
--- a/api_test/CMakeLists.txt
+++ b/api_test/CMakeLists.txt
@@ -6,9 +6,9 @@ add_executable(api_test
 )
 include_directories(
   ${PROJECT_SOURCE_DIR}/src/include
-  ${PROJECT_BINARY_DIR}/src/include
+  ${PROJECT_BINARY_DIR}/src
   ${PROJECT_SOURCE_DIR}/extensions/include
-  ${PROJECT_BINARY_DIR}/extensions/include
+  ${PROJECT_BINARY_DIR}/extensions
 )
 if(CMARK_SHARED)
   target_link_libraries(api_test libcmark-gfm-extensions libcmark-gfm)
@@ -24,7 +24,7 @@ if(MSVC)
   else()
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /W4")
   endif()
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /wd4706 /D_CRT_SECURE_NO_WARNINGS")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /wd4706 /wd5105 /D_CRT_SECURE_NO_WARNINGS")
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /TP")
 elseif(CMAKE_COMPILER_IS_GNUCC OR "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang")
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -std=c99 -pedantic")
diff --git a/api_test/main.c b/api_test/main.c
index 1051c2904..2e497ce95 100644
--- a/api_test/main.c
+++ b/api_test/main.c
@@ -1192,7 +1192,7 @@ static void inline_only_opt(test_batch_runner *runner) {
   cmark_node_free(doc);
 }
 
-static void check_markdown_plaintext(test_batch_runner *runner, char *markdown) {
+static void check_markdown_plaintext(test_batch_runner *runner, const char *markdown) {
   cmark_node *doc = cmark_parse_document(markdown, strlen(markdown), CMARK_OPT_PRESERVE_WHITESPACE);
   cmark_node *pg = cmark_node_first_child(doc);
   INT_EQ(runner, cmark_node_get_type(pg), CMARK_NODE_PARAGRAPH, "markdown '%s' did not produce a paragraph node", markdown);
@@ -1228,7 +1228,7 @@ static void preserve_whitespace_opt(test_batch_runner *runner) {
   check_markdown_plaintext(runner, "\nHello\n");
 }
 
-static void check_markdown_attributes_node(test_batch_runner *runner, char *markdown, cmark_node_type expectedType, char *expectedAttributes) {
+static void check_markdown_attributes_node(test_batch_runner *runner, const char *markdown, cmark_node_type expectedType, const char *expectedAttributes) {
   cmark_node *doc = cmark_parse_document(markdown, strlen(markdown), CMARK_OPT_DEFAULT);
   cmark_node *pg = cmark_node_first_child(doc);
   INT_EQ(runner, cmark_node_get_type(pg), CMARK_NODE_PARAGRAPH, "markdown '%s' did not produce a paragraph node", markdown);
diff --git a/extensions/CMakeLists.txt b/extensions/CMakeLists.txt
index 4977c98c3..9bbec1f47 100644
--- a/extensions/CMakeLists.txt
+++ b/extensions/CMakeLists.txt
@@ -15,7 +15,7 @@ set(LIBRARY_SOURCES
 
 include_directories(
   ${PROJECT_SOURCE_DIR}/src/include
-  ${PROJECT_BINARY_DIR}/src/include
+  ${PROJECT_BINARY_DIR}/src
 )
 
 include (GenerateExportHeader)
@@ -86,7 +86,7 @@ install(TARGETS ${CMARK_INSTALL}
 if (CMARK_SHARED OR CMARK_STATIC)
   install(FILES
   ${CMAKE_CURRENT_SOURCE_DIR}/include/cmark-gfm-core-extensions.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/cmark-gfm-extensions_export.h
+  ${CMAKE_CURRENT_SOURCE_DIR}/include/extensions-export.h
   DESTINATION include
   )
 
@@ -98,14 +98,10 @@ include(CheckIncludeFile)
 include(CheckCSourceCompiles)
 include(CheckCSourceRuns)
 include(CheckSymbolExists)
-CHECK_INCLUDE_FILE(stdbool.h HAVE_STDBOOL_H)
+CHECK_INCLUDE_FILE(unistd.h HAVE_UNISTD_H)
 CHECK_C_SOURCE_COMPILES(
   "int main() { __builtin_expect(0,0); return 0; }"
   HAVE___BUILTIN_EXPECT)
-CHECK_C_SOURCE_COMPILES("
-  int f(void) __attribute__ (());
-  int main() { return 0; }
-" HAVE___ATTRIBUTE__)
 
 # Always compile with warnings
 if(MSVC)
@@ -115,7 +111,7 @@ if(MSVC)
   else()
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /W4")
   endif()
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /WX /wd4706 /wd4204 /wd4221 /wd4100 /D_CRT_SECURE_NO_WARNINGS")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /WX /wd4706 /wd4204 /wd4221 /wd4100 /wd5105 /D_CRT_SECURE_NO_WARNINGS")
 elseif(CMAKE_COMPILER_IS_GNUCC OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -Wno-unused-parameter -std=c99 -pedantic")
 endif()
diff --git a/extensions/include/cmark-gfm-core-extensions.h b/extensions/include/cmark-gfm-core-extensions.h
index 51103e616..20da8d6e3 100644
--- a/extensions/include/cmark-gfm-core-extensions.h
+++ b/extensions/include/cmark-gfm-core-extensions.h
@@ -6,7 +6,7 @@ extern "C" {
 #endif
 
 #include "cmark-gfm-extension_api.h"
-#include "cmark-gfm-extensions_export.h"
+#include "extensions-export.h"
 #include "cmark-gfm_config.h" // for bool
 #include <stdint.h>
 
diff --git a/extensions/include/cmark-gfm-extensions_export.h b/extensions/include/cmark-gfm-extensions_export.h
deleted file mode 100644
index 69c0bd787..000000000
--- a/extensions/include/cmark-gfm-extensions_export.h
+++ /dev/null
@@ -1,42 +0,0 @@
-
-#ifndef CMARK_GFM_EXTENSIONS_EXPORT_H
-#define CMARK_GFM_EXTENSIONS_EXPORT_H
-
-#ifdef CMARK_GFM_EXTENSIONS_STATIC_DEFINE
-#  define CMARK_GFM_EXTENSIONS_EXPORT
-#  define CMARK_GFM_EXTENSIONS_NO_EXPORT
-#else
-#  ifndef CMARK_GFM_EXTENSIONS_EXPORT
-#    ifdef libcmark_gfm_extensions_EXPORTS
-        /* We are building this library */
-#      define CMARK_GFM_EXTENSIONS_EXPORT __attribute__((visibility("default")))
-#    else
-        /* We are using this library */
-#      define CMARK_GFM_EXTENSIONS_EXPORT __attribute__((visibility("default")))
-#    endif
-#  endif
-
-#  ifndef CMARK_GFM_EXTENSIONS_NO_EXPORT
-#    define CMARK_GFM_EXTENSIONS_NO_EXPORT __attribute__((visibility("hidden")))
-#  endif
-#endif
-
-#ifndef CMARK_GFM_EXTENSIONS_DEPRECATED
-#  define CMARK_GFM_EXTENSIONS_DEPRECATED __attribute__ ((__deprecated__))
-#endif
-
-#ifndef CMARK_GFM_EXTENSIONS_DEPRECATED_EXPORT
-#  define CMARK_GFM_EXTENSIONS_DEPRECATED_EXPORT CMARK_GFM_EXTENSIONS_EXPORT CMARK_GFM_EXTENSIONS_DEPRECATED
-#endif
-
-#ifndef CMARK_GFM_EXTENSIONS_DEPRECATED_NO_EXPORT
-#  define CMARK_GFM_EXTENSIONS_DEPRECATED_NO_EXPORT CMARK_GFM_EXTENSIONS_NO_EXPORT CMARK_GFM_EXTENSIONS_DEPRECATED
-#endif
-
-#if 0 /* DEFINE_NO_DEPRECATED */
-#  ifndef CMARK_GFM_EXTENSIONS_NO_DEPRECATED
-#    define CMARK_GFM_EXTENSIONS_NO_DEPRECATED
-#  endif
-#endif
-
-#endif /* CMARK_GFM_EXTENSIONS_EXPORT_H */
diff --git a/extensions/include/extensions-export.h b/extensions/include/extensions-export.h
new file mode 100644
index 000000000..f91b8564c
--- /dev/null
+++ b/extensions/include/extensions-export.h
@@ -0,0 +1,60 @@
+#ifndef CMARK_GFM_EXTENSIONS_EXPORT_H
+#define CMARK_GFM_EXTENSIONS_EXPORT_H
+
+#ifdef CMARK_USE_CMAKE_HEADERS
+// if the CMake config header exists, use that instead of this Swift package prebuilt one
+// we need to undefine the header guard, since export.h uses the same one
+#undef CMARK_GFM_EXTENSIONS_EXPORT_H
+#include "cmark-gfm-extensions_export.h"
+#else
+
+#ifdef CMARK_GFM_EXTENSIONS_STATIC_DEFINE
+#  define CMARK_GFM_EXTENSIONS_EXPORT
+#  define CMARK_GFM_EXTENSIONS_NO_EXPORT
+#else
+#  if defined(_WIN32)
+#    ifndef CMARK_GFM_EXTENSIONS_EXPORT
+#      ifdef libcmark_gfm_extensions_EXPORTS
+#        define CMARK_GFM_EXTENSIONS_EXPORT __declspec(dllexport)
+#      else
+#        define CMARK_GFM_EXTENSIONS_EXPORT __declspec(dllimport)
+#      endif
+#    endif
+
+#    ifndef CMARK_GFM_EXTENSIONS_NO_EXPORT
+#      define CMARK_GFM_EXTENSIONS_NO_EXPORT
+#    endif
+#  else
+#    ifndef CMARK_GFM_EXTENSIONS_EXPORT
+#      ifdef libcmark_gfm_extensions_EXPORTS
+#        define CMARK_GFM_EXTENSIONS_EXPORT __attribute__((__visibility__("default")))
+#      else
+#        define CMARK_GFM_EXTENSIONS_EXPORT __attribute__((__visibility__("default")))
+#      endif
+#    endif
+
+#    ifndef CMARK_GFM_EXTENSIONS_NO_EXPORT
+#      define CMARK_GFM_EXTENSIONS_NO_EXPORT __attribute__((__visibility__("hidden")))
+#    endif
+#  endif
+#endif
+
+#ifndef CMARK_GFM_EXTENSIONS_DEPRECATED
+#  if defined(_WIN32)
+#    define CMARK_GFM_EXTENSIONS_DEPRECATED __declspec(deprecated)
+#  else
+#    define CMARK_GFM_EXTENSIONS_DEPRECATED __attribute__ ((__deprecated__))
+#  endif
+#endif
+
+#ifndef CMARK_GFM_EXTENSIONS_DEPRECATED_EXPORT
+#  define CMARK_GFM_EXTENSIONS_DEPRECATED_EXPORT CMARK_GFM_EXTENSIONS_EXPORT CMARK_GFM_EXTENSIONS_DEPRECATED
+#endif
+
+#ifndef CMARK_GFM_EXTENSIONS_DEPRECATED_NO_EXPORT
+#  define CMARK_GFM_EXTENSIONS_DEPRECATED_NO_EXPORT CMARK_GFM_EXTENSIONS_NO_EXPORT CMARK_GFM_EXTENSIONS_DEPRECATED
+#endif
+
+#endif /* CMARK_GFM_EXTENSIONS_EXPORT_H */
+
+#endif /* "cmark-gfm-extensions_export.h" */
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index b7018903c..faabffa4a 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -45,7 +45,7 @@ set(PROGRAM_SOURCES "${PROJECT_SOURCE_DIR}/bin/main.c")
 include_directories(include ${CMAKE_CURRENT_BINARY_DIR})
 include_directories(
   ${PROJECT_SOURCE_DIR}/extensions/include
-  ${PROJECT_BINARY_DIR}/extensions/include
+  ${PROJECT_BINARY_DIR}/extensions
 )
 
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/cmark-gfm_version.h.in
@@ -152,12 +152,25 @@ if(CMARK_SHARED OR CMARK_STATIC)
     ${CMAKE_CURRENT_SOURCE_DIR}/include/cmark-gfm.h
     ${CMAKE_CURRENT_SOURCE_DIR}/include/cmark-gfm_config.h
     ${CMAKE_CURRENT_SOURCE_DIR}/include/cmark-gfm-extension_api.h
-    ${CMAKE_CURRENT_SOURCE_DIR}/include/cmark-gfm_export.h
+    ${CMAKE_CURRENT_SOURCE_DIR}/include/export.h
     ${CMAKE_CURRENT_SOURCE_DIR}/include/cmark-gfm_version.h
     DESTINATION include
     )
 
   install(EXPORT cmark-gfm DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake)
+
+  set(CMARK_TARGETS_FILE ${CMAKE_CURRENT_BINARY_DIR}/cmarkTargets.cmake)
+  export(TARGETS ${CMARK_INSTALL} FILE ${CMARK_TARGETS_FILE})
+
+  if(CMARK_THREADING AND NOT APPLE AND NOT MSVC)
+    if(CMARK_SHARED)
+      target_link_libraries(${LIBRARY} pthread)
+    endif(CMARK_SHARED)
+
+    if(CMARK_STATIC)
+      target_link_libraries(${STATICLIBRARY} pthread)
+    endif(CMARK_STATIC)
+  endif()
 endif()
 
 # Feature tests
@@ -165,14 +178,10 @@ include(CheckIncludeFile)
 include(CheckCSourceCompiles)
 include(CheckCSourceRuns)
 include(CheckSymbolExists)
-CHECK_INCLUDE_FILE(stdbool.h HAVE_STDBOOL_H)
+CHECK_INCLUDE_FILE(unistd.h HAVE_UNISTD_H)
 CHECK_C_SOURCE_COMPILES(
   "int main() { __builtin_expect(0,0); return 0; }"
   HAVE___BUILTIN_EXPECT)
-CHECK_C_SOURCE_COMPILES("
-  int f(void) __attribute__ (());
-  int main() { return 0; }
-" HAVE___ATTRIBUTE__)
 
 CONFIGURE_FILE(
   ${CMAKE_CURRENT_SOURCE_DIR}/config.h.in
@@ -186,7 +195,7 @@ if(MSVC)
   else()
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /W4")
   endif()
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /WX /wd4706 /wd4204 /wd4221 /wd4100 /D_CRT_SECURE_NO_WARNINGS")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /WX /wd4706 /wd4204 /wd4221 /wd4100 /wd5105 /D_CRT_SECURE_NO_WARNINGS")
 elseif(CMAKE_COMPILER_IS_GNUCC OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -Wno-unused-parameter -std=c99 -pedantic")
 endif()
diff --git a/src/config.h.in b/src/config.h.in
index 65702b2e0..f8f767a8b 100644
--- a/src/config.h.in
+++ b/src/config.h.in
@@ -5,26 +5,18 @@
 extern "C" {
 #endif
 
-#cmakedefine HAVE_STDBOOL_H
-
-#ifdef HAVE_STDBOOL_H
+#if __STDC_VERSION__ >= 199901l
   #include <stdbool.h>
 #elif !defined(__cplusplus)
   typedef char bool;
 #endif
 
-#cmakedefine HAVE___BUILTIN_EXPECT
+#cmakedefine HAVE_UNISTD_H
 
-#cmakedefine HAVE___ATTRIBUTE__
+#cmakedefine HAVE___BUILTIN_EXPECT
 
 #cmakedefine CMARK_THREADING
 
-#ifdef HAVE___ATTRIBUTE__
-  #define CMARK_ATTRIBUTE(list) __attribute__ (list)
-#else
-  #define CMARK_ATTRIBUTE(list)
-#endif
-
 #ifndef CMARK_INLINE
   #if defined(_MSC_VER) && !defined(__cplusplus)
     #define CMARK_INLINE __inline
diff --git a/src/include/cmark-gfm.h b/src/include/cmark-gfm.h
index 14ab95f4a..aee012955 100644
--- a/src/include/cmark-gfm.h
+++ b/src/include/cmark-gfm.h
@@ -3,7 +3,7 @@
 
 #include <stdio.h>
 #include <stdint.h>
-#include "cmark-gfm_export.h"
+#include "export.h"
 #include "cmark-gfm_version.h"
 
 #ifdef __cplusplus
@@ -807,7 +807,7 @@ const char *cmark_version_string(void);
  * John MacFarlane, Vicent Marti,  Kārlis Gaņģis, Nick Wellnhofer.
  */
 
-#ifndef CMARK_NO_SHORT_NAMES
+#if !defined(CMARK_NO_SHORT_NAMES)
 #define NODE_DOCUMENT CMARK_NODE_DOCUMENT
 #define NODE_BLOCK_QUOTE CMARK_NODE_BLOCK_QUOTE
 #define NODE_LIST CMARK_NODE_LIST
diff --git a/src/include/cmark-gfm_config.h b/src/include/cmark-gfm_config.h
index 1f96cc558..7d331915b 100644
--- a/src/include/cmark-gfm_config.h
+++ b/src/include/cmark-gfm_config.h
@@ -1,30 +1,36 @@
 #ifndef CMARK_CONFIG_H
 #define CMARK_CONFIG_H
 
+#ifdef CMARK_USE_CMAKE_HEADERS
+// if the CMake config header exists, use that instead of this Swift package prebuilt one
+// we need to undefine the header guard, since config.h uses the same one
+#undef CMARK_CONFIG_H
+#include "config.h"
+#else
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#define HAVE_STDBOOL_H
-
-#ifdef HAVE_STDBOOL_H
+#if __STDC_VERSION__ >= 199901l
   #include <stdbool.h>
 #elif !defined(__cplusplus)
   typedef char bool;
 #endif
 
-#define HAVE___BUILTIN_EXPECT
+#if defined(__has_include)
+#  if __has_include(<unistd.h>)
+#    define HAVE_UNISTD_H
+#  endif
+#elif defined(unix) || defined(__unix__) || defined(__unix) || defined(__APPLE__)
+  // Apple Clang does not define any of the unix symbols, even though it provides unistd.h
+#  define HAVE_UNISTD_H
+#endif
 
-#define HAVE___ATTRIBUTE__
+#define HAVE___BUILTIN_EXPECT
 
 #define CMARK_THREADING
 
-#ifdef HAVE___ATTRIBUTE__
-  #define CMARK_ATTRIBUTE(list) __attribute__ (list)
-#else
-  #define CMARK_ATTRIBUTE(list)
-#endif
-
 #ifndef CMARK_INLINE
   #if defined(_MSC_VER) && !defined(__cplusplus)
     #define CMARK_INLINE __inline
@@ -75,4 +81,6 @@ CMARK_INLINE int c99_snprintf(char *outBuf, size_t size, const char *format, ...
 }
 #endif
 
-#endif
+#endif /* not CMARK_USE_CMAKE_HEADERS */
+
+#endif /* not CMARK_CONFIG_H */
diff --git a/src/include/cmark_ctype.h b/src/include/cmark_ctype.h
index 67c1cb037..4c2457e8c 100644
--- a/src/include/cmark_ctype.h
+++ b/src/include/cmark_ctype.h
@@ -5,7 +5,7 @@
 extern "C" {
 #endif
 
-#include "cmark-gfm_export.h"
+#include "export.h"
 
 /** Locale-independent versions of functions from ctype.h.
  * We want cmark to behave the same no matter what the system locale.
diff --git a/src/include/cmark-gfm_export.h b/src/include/export.h
similarity index 61%
rename from src/include/cmark-gfm_export.h
rename to src/include/export.h
index 7247214be..c219c6f54 100644
--- a/src/include/cmark-gfm_export.h
+++ b/src/include/export.h
@@ -1,7 +1,13 @@
-
 #ifndef CMARK_GFM_EXPORT_H
 #define CMARK_GFM_EXPORT_H
 
+#ifdef CMARK_USE_CMAKE_HEADERS
+// if the CMake config header exists, use that instead of this Swift package prebuilt one
+// we need to undefine the header guard, since export.h uses the same one
+#undef CMARK_GFM_EXPORT_H
+#include "cmark-gfm_export.h"
+#else
+
 #ifdef CMARK_GFM_STATIC_DEFINE
 #  define CMARK_GFM_EXPORT
 #  define CMARK_GFM_NO_EXPORT
@@ -15,11 +21,7 @@
 #    define CMARK_GFM_NO_EXPORT
 #  else
 #    if defined(libcmark_gfm_EXPORTS)
-#      if defined(__linux__)
-#        define CMARK_GFM_EXPORT __attribute__((__visibility__("protected")))
-#      else
-#        define CMARK_GFM_EXPORT __attribute__((__visibility__("default")))
-#      endif
+#      define CMARK_GFM_EXPORT __attribute__((__visibility__("default")))
 #    else
 #      define CMARK_GFM_EXPORT __attribute__((__visibility__("default")))
 #    endif
@@ -28,7 +30,11 @@
 #endif
 
 #ifndef CMARK_GFM_DEPRECATED
-#  define CMARK_GFM_DEPRECATED __attribute__ ((__deprecated__))
+#  if defined(_WIN32)
+#    define CMARK_GFM_DEPRECATED __declspec(deprecated)
+#  else
+#    define CMARK_GFM_DEPRECATED __attribute__ ((__deprecated__))
+#  endif
 #endif
 
 #ifndef CMARK_GFM_DEPRECATED_EXPORT
@@ -39,10 +45,6 @@
 #  define CMARK_GFM_DEPRECATED_NO_EXPORT CMARK_GFM_NO_EXPORT CMARK_GFM_DEPRECATED
 #endif
 
-#if 0 /* DEFINE_NO_DEPRECATED */
-#  ifndef CMARK_GFM_NO_DEPRECATED
-#    define CMARK_GFM_NO_DEPRECATED
-#  endif
-#endif
+#endif /* not CMARK_USE_CMAKE_HEADERS */
 
-#endif /* CMARK_GFM_EXPORT_H */
+#endif /* not CMARK_GFM_EXPORT_H */
diff --git a/src/include/mutex.h b/src/include/mutex.h
index 7335d8225..d2ad4787b 100644
--- a/src/include/mutex.h
+++ b/src/include/mutex.h
@@ -5,7 +5,7 @@
 
 #ifdef CMARK_THREADING
 
-#if __has_include(<unistd.h>)
+#ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
 
@@ -30,8 +30,9 @@ pthread_mutex_lock(&NAME##_lock);
 
 #elif defined(_WIN32) // building for windows
 
-#define _WIN32_WINNT 0x0600
-#include <synchapi.h>
+#define _WIN32_WINNT 0x0600 // minimum target of Windows Vista
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
 
 #define CMARK_DEFINE_ONCE(NAME) static INIT_ONCE NAME##_once = INIT_ONCE_STATIC_INIT;
 
diff --git a/src/inlines.c b/src/inlines.c
index 7d4a8d451..e97f5e568 100644
--- a/src/inlines.c
+++ b/src/inlines.c
@@ -1100,7 +1100,7 @@ static bufsize_t manual_scan_attribute_attributes(cmark_chunk *input, bufsize_t
 
 static cmark_node *handle_close_bracket_attribute(cmark_parser *parser, subject *subj, bracket *opener) {
   bufsize_t startattributes, endattributes;
-  cmark_chunk attributes;
+  cmark_chunk attributes = CMARK_CHUNK_EMPTY;
   bufsize_t n;
   cmark_node *inl;
   cmark_chunk raw_label;