diff --git a/cfg/posix.cfg b/cfg/posix.cfg
index d4e8e5ce6..c17e0c153 100644
--- a/cfg/posix.cfg
+++ b/cfg/posix.cfg
@@ -1993,6 +1993,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
       <not-bool/>
     </arg>
   </function>
+  <!-- https://man7.org/linux/man-pages/man3/strncasecmp.3.html -->
   <!-- int strncasecmp(const char *s1, const char *s2, size_t n); -->
   <function name="strncasecmp">
     <pure/>
@@ -2013,6 +2014,27 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
       <valid>0:</valid>
     </arg>
   </function>
+  <!-- https://man7.org/linux/man-pages/man3/wcsncasecmp.3.html -->
+  <!-- int wcsncasecmp(const wchar_t *s1, const wchar_t *s2, size_t n) -->
+  <function name="wcsncasecmp">
+    <pure/>
+    <use-retval/>
+    <noreturn>false</noreturn>
+    <leak-ignore/>
+    <returnValue type="int"/>
+    <arg nr="1" direction="in">
+      <not-null/>
+      <not-uninit/>
+    </arg>
+    <arg nr="2" direction="in">
+      <not-null/>
+      <not-uninit/>
+    </arg>
+    <arg nr="3" direction="in">
+      <not-bool/>
+      <valid>0:</valid>
+    </arg>
+  </function>
   <!-- ssize_t sendfile(int out_fd, int in_fd, off_t *offset, size_t count); -->
   <function name="sendfile">
     <leak-ignore/>
diff --git a/test/cfg/posix.c b/test/cfg/posix.c
index 0557c2dc1..97f7bd438 100644
--- a/test/cfg/posix.c
+++ b/test/cfg/posix.c
@@ -31,6 +31,15 @@
 #include <wchar.h>
 #include <string.h>
 
+int nullPointer_wcsncasecmp(const wchar_t *s1, const wchar_t *s2, size_t n)
+{
+    // cppcheck-suppress nullPointer
+    (void)wcsncasecmp(NULL,s2,n);
+    // cppcheck-suppress nullPointer
+    (void)wcsncasecmp(s1,NULL,n);
+    return wcsncasecmp(s1,s2,n);
+}
+
 int uninitvar_wcwidth(const wchar_t c)
 {
     wchar_t wc;