diff --git a/include/gk_externs.h b/include/gk_externs.h
index 2c0fdd9..8338217 100644
--- a/include/gk_externs.h
+++ b/include/gk_externs.h
@@ -10,15 +10,25 @@
 #ifndef _GK_EXTERNS_H_
 #define _GK_EXTERNS_H_
 
+// Windows does not support _Thread_local. Use appropriate aliases
+// Reference: https://stackoverflow.com/a/18298965
+#ifndef thread_local
+#if __STDC_VERSION__ >= 201112 && !defined __STDC_NO_THREADS__
+#define thread_local _Thread_local
+#elif defined _MSC_VER
+#define thread_local __declspec(thread)
+#elif defined __GNUC__
+#define thread_local __thread
+#else
+#error "Cannot define thread_local"
+#endif
+#endif
 
-/*************************************************************************
-* Extern variable definition. Hopefully, the __thread makes them thread-safe.
-**************************************************************************/
 #ifndef _GK_ERROR_C_
 /* declared in error.c */
-extern __thread int gk_cur_jbufs;
-extern __thread jmp_buf gk_jbufs[];
-extern __thread jmp_buf gk_jbuf;
+extern thread_local int gk_cur_jbufs;
+extern thread_local jmp_buf gk_jbufs[];
+extern thread_local jmp_buf gk_jbuf;
 
 #endif
 
diff --git a/src/error.c b/src/error.c
index e2a18cf..e053537 100644
--- a/src/error.c
+++ b/src/error.c
@@ -19,17 +19,17 @@ This file contains functions dealing with error reporting and termination
 /* These are the jmp_buf for the graceful exit in case of severe errors.
    Multiple buffers are defined to allow for recursive invokation. */
 #define MAX_JBUFS 128
-__thread int gk_cur_jbufs=-1;
-__thread jmp_buf gk_jbufs[MAX_JBUFS];
-__thread jmp_buf gk_jbuf;
+thread_local int gk_cur_jbufs=-1;
+thread_local jmp_buf gk_jbufs[MAX_JBUFS];
+thread_local jmp_buf gk_jbuf;
 
 typedef void (*gksighandler_t)(int);
 
 /* These are the holders of the old singal handlers for the trapped signals */
-static __thread gksighandler_t old_SIGMEM_handler;  /* Custom signal */
-static __thread gksighandler_t old_SIGERR_handler;  /* Custom signal */
-static __thread gksighandler_t old_SIGMEM_handlers[MAX_JBUFS];  /* Custom signal */
-static __thread gksighandler_t old_SIGERR_handlers[MAX_JBUFS];  /* Custom signal */
+static thread_local gksighandler_t old_SIGMEM_handler;  /* Custom signal */
+static thread_local gksighandler_t old_SIGERR_handler;  /* Custom signal */
+static thread_local gksighandler_t old_SIGMEM_handlers[MAX_JBUFS];  /* Custom signal */
+static thread_local gksighandler_t old_SIGERR_handlers[MAX_JBUFS];  /* Custom signal */
 
 /* The following is used to control if the gk_errexit() will actually abort or not.
    There is always a single copy of this variable */
@@ -178,7 +178,7 @@ char *gk_strerror(int errnum)
   return strerror(errnum);
 #else 
 #ifndef SUNOS
-  static __thread char buf[1024];
+  static thread_local char buf[1024];
 
   strerror_r(errnum, buf, 1024);
 
diff --git a/src/memory.c b/src/memory.c
index e6dc99c..616436d 100644
--- a/src/memory.c
+++ b/src/memory.c
@@ -16,7 +16,7 @@ can be used to define other memory allocation routines.
 #include <GKlib.h>
 
 /* This is for the global mcore that tracks all heap allocations */
-static __thread gk_mcore_t *gkmcore = NULL;
+static thread_local gk_mcore_t *gkmcore = NULL;
 
 
 /*************************************************************************/