diff --git a/vm/image.cpp b/vm/image.cpp
index b394885730..fe607ad747 100644
--- a/vm/image.cpp
+++ b/vm/image.cpp
@@ -200,12 +200,26 @@ bool factor_vm::read_embedded_image_footer(FILE* file,
   return footer->magic == image_magic;
 }
 
+char *threadsafe_strerror(int errnum) {
+  char *buf = (char *) malloc(STRERROR_BUFFER_SIZE);
+  if(!buf) {
+    fatal_error("Out of memory in threadsafe_strerror", 0);
+  }
+  int ret = THREADSAFE_STRERROR(errnum, buf, STRERROR_BUFFER_SIZE);
+  if(ret != 0) {
+    std::cout << "Truncated output from THREADSAFE_STRERROR, error code:" << errnum << ", ret: " << ret << std::endl;
+  }
+  return buf;
+}
+
 FILE* factor_vm::open_image(vm_parameters* p) {
   if (p->embedded_image) {
     FILE* file = OPEN_READ(p->executable_path);
     if (file == NULL) {
       std::cout << "Cannot open embedded image" << std::endl;
-      std::cout << strerror(errno) << std::endl;
+      char *msg = threadsafe_strerror(errno);
+      std::cout << "strerror: " << msg << std::endl;
+      free(msg);
       exit(1);
     }
     embedded_image_footer footer;
@@ -225,7 +239,9 @@ void factor_vm::load_image(vm_parameters* p) {
   FILE* file = open_image(p);
   if (file == NULL) {
     std::cout << "Cannot open image file: " << p->image_path << std::endl;
-    std::cout << strerror(errno) << std::endl;
+    char *msg = threadsafe_strerror(errno);
+    std::cout << "strerror: " << msg << std::endl;
+    free(msg);
     exit(1);
   }
 
@@ -265,7 +281,9 @@ bool factor_vm::save_image(const vm_char* saving_filename,
   file = OPEN_WRITE(saving_filename);
   if (file == NULL) {
     std::cout << "Cannot open image file for writing: " << saving_filename << std::endl;
-    std::cout << strerror(errno) << std::endl;
+    char *msg = threadsafe_strerror(errno);
+    std::cout << "strerror: " << msg << std::endl;
+    free(msg);
     return false;
   }
 
@@ -295,8 +313,12 @@ bool factor_vm::save_image(const vm_char* saving_filename,
     ok = false;
   safe_fclose(file);
 
-  if (!ok)
-    std::cout << "save-image failed: " << strerror(errno) << std::endl;
+  if (!ok) {
+    std::cout << "save-image failed." << std::endl;
+    char *msg = threadsafe_strerror(errno);
+    std::cout << "strerror: " << msg << std::endl;
+    free(msg);
+  }
   else
     move_file(saving_filename, filename);
 
diff --git a/vm/image.hpp b/vm/image.hpp
index efc0c82856..e1a71c6781 100644
--- a/vm/image.hpp
+++ b/vm/image.hpp
@@ -3,6 +3,8 @@ namespace factor {
 static const cell image_magic = 0x0f0e0d0c;
 static const cell image_version = 4;
 
+const size_t STRERROR_BUFFER_SIZE = 1024;
+
 struct embedded_image_footer {
   cell magic;
   cell image_offset;
diff --git a/vm/os-genunix.hpp b/vm/os-genunix.hpp
index 82773a7944..dee563a968 100644
--- a/vm/os-genunix.hpp
+++ b/vm/os-genunix.hpp
@@ -5,5 +5,4 @@ namespace factor {
 void early_init();
 const char* vm_executable_path();
 const char* default_image_path();
-
 }
diff --git a/vm/os-unix.cpp b/vm/os-unix.cpp
index d5122545e9..2b816b361a 100644
--- a/vm/os-unix.cpp
+++ b/vm/os-unix.cpp
@@ -502,4 +502,8 @@ void abort() {
   ::abort();
 }
 
+int THREADSAFE_STRERROR(int errnum, char *buf, size_t buflen) {
+  return strerror_r(errnum, buf, buflen);
+}
+
 }
diff --git a/vm/os-unix.hpp b/vm/os-unix.hpp
index d6b7bea93c..036399f91b 100644
--- a/vm/os-unix.hpp
+++ b/vm/os-unix.hpp
@@ -46,4 +46,6 @@ void move_file(const vm_char* path1, const vm_char* path2);
 
 static inline void breakpoint() { __builtin_trap(); }
 
+int THREADSAFE_STRERROR(int errnum, char *buf, size_t buflen);
+
 }
diff --git a/vm/os-windows.cpp b/vm/os-windows.cpp
index f83f67f91d..4fee07f7e9 100644
--- a/vm/os-windows.cpp
+++ b/vm/os-windows.cpp
@@ -373,4 +373,6 @@ void factor_vm::end_sampling_profiler_timer() {
 
 void abort() { ::abort(); }
 
+int THREADSAFE_STRERROR(int errnum, char *buf, size_t buflen) {
+  return strerror_s(buf, buflen, errnum);
 }
diff --git a/vm/os-windows.hpp b/vm/os-windows.hpp
index 2dab596c4d..de00b89f0f 100644
--- a/vm/os-windows.hpp
+++ b/vm/os-windows.hpp
@@ -93,4 +93,6 @@ inline static void breakpoint() { DebugBreak(); }
 #define FUNCTION_TOC_POINTER(ptr) ptr
 
 extern HANDLE boot_thread;
+
+int THREADSAFE_STRERROR(int errnum, char *buf, size_t buflen);
 }