diff --git a/xs/src/libslic3r/Print.cpp b/xs/src/libslic3r/Print.cpp
index 617b487d2d..ef38df35e0 100644
--- a/xs/src/libslic3r/Print.cpp
+++ b/xs/src/libslic3r/Print.cpp
@@ -1342,7 +1342,7 @@ public:
     inline unsigned layers() const { return layers_rst_.size(); }
 
     inline void drawPolygon(const ExPolygon& p, unsigned lyr) {
-        assert(lyr_id < layers_rst_.size());
+        assert(lyr < layers_rst_.size());
         layers_rst_[lyr].first.draw(p);
     }
 
diff --git a/xs/src/libslic3r/Rasterizer/Rasterizer.cpp b/xs/src/libslic3r/Rasterizer/Rasterizer.cpp
index ab83c5ec6d..ff5b95c352 100644
--- a/xs/src/libslic3r/Rasterizer/Rasterizer.cpp
+++ b/xs/src/libslic3r/Rasterizer/Rasterizer.cpp
@@ -16,12 +16,6 @@
 #include <agg/agg_path_storage.h>
 
 // For png compression
-//#if !((_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600) && ! _GNU_SOURCE)
-//inline char *strerror_r(int errnum, char *buf, size_t buflen) {
-//    strerror_s(buf, buflen, errnum);
-//    return buf;
-//}
-//#endif
 #include <png/writer.hpp>
 
 namespace Slic3r {
diff --git a/xs/src/png/error.hpp b/xs/src/png/error.hpp
index f7d6d7b5f1..c67f97630b 100644
--- a/xs/src/png/error.hpp
+++ b/xs/src/png/error.hpp
@@ -94,20 +94,27 @@ namespace png
         static std::string thread_safe_strerror(int errnum)
         {
 #define ERRBUF_SIZE 512
-            char buf[ERRBUF_SIZE] = { 0 };
 
-//#ifdef HAVE_STRERROR_S
+#ifdef HAVE_STRERROR_S
+            char buf[ERRBUF_SIZE] = { 0 };
             strerror_s(buf, ERRBUF_SIZE, errnum);
             return std::string(buf);
-//#else
-//#if (_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600) && !_GNU_SOURCE
-//            strerror_r(errnum, buf, ERRBUF_SIZE);
-//            return std::string(buf);
-//#else
-//            /* GNU variant can return a pointer to static buffer instead of buf */
-//            return std::string(strerror_r(errnum, buf, ERRBUF_SIZE));
-//#endif
-//#endif
+#else
+#if (_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600) && !_GNU_SOURCE
+            char buf[ERRBUF_SIZE] = { 0 };
+            strerror_r(errnum, buf, ERRBUF_SIZE);
+            return std::string(buf);
+#elif _GNU_SOURCE
+            /* GNU variant can return a pointer to static buffer instead of buf */
+            char buf[ERRBUF_SIZE] = { 0 };
+            return std::string(strerror_r(errnum, buf, ERRBUF_SIZE));
+#else
+            return std::string("An error occured with errnum ") +
+                    std::to_string(errnum) +
+                    ". Converting to the appropriate error message is disabled"
+                    "in this instance of the png++ library.";
+#endif
+#endif
 
 #undef ERRBUF_SIZE
         }