diff --git a/source/lib/posix/posix.cpp b/source/lib/posix/posix.cpp
index 21297fbb07..c4d9e68cab 100644
--- a/source/lib/posix/posix.cpp
+++ b/source/lib/posix/posix.cpp
@@ -101,3 +101,24 @@ wchar_t* wcsdup(const wchar_t* str)
 	return dst;
 }
 #endif
+
+#if EMULATE_WCSCASECMP
+int wcscasecmp (const wchar_t* s1, const wchar_t* s2)
+{
+	wint_t a1, a2;
+
+	if (s1 == s2)
+		return 0;
+
+	do
+	{
+		a1 = towlower(*s1++);
+		a2 = towlower(*s2++);
+		if (a1 == L'\0')
+			break;
+	}
+	while (a1 == a2);
+
+	return a1 - a2;
+}
+#endif
diff --git a/source/lib/posix/posix.h b/source/lib/posix/posix.h
index 618247ab8c..deb0b86e25 100644
--- a/source/lib/posix/posix.h
+++ b/source/lib/posix/posix.h
@@ -96,14 +96,19 @@ need only be renamed (e.g. _open, _stat).
 
 #if OS_MACOSX
 # define EMULATE_WCSDUP 1
+# define EMULATE_WCSCASECMP 1
 #else
 # define EMULATE_WCSDUP 0
+# define EMULATE_WCSCASECMP 0
 #endif
 
 #if EMULATE_WCSDUP
 extern wchar_t* wcsdup(const wchar_t* str);
 #endif
 
+#if EMULATE_WCSCASECMP
+extern int wcscasecmp(const wchar_t* s1, const wchar_t* s2);
+#endif
 
 // rint*, fminf, fpclassify (too few/diverse to make separate HAVE_ for each)
 #if HAVE_C99 || ICC_VERSION || GCC_VERSION