diff --git a/cfg/posix.cfg b/cfg/posix.cfg
index f79f473ab..5af9a3f20 100644
--- a/cfg/posix.cfg
+++ b/cfg/posix.cfg
@@ -4740,6 +4740,60 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
     </arg>
     <warn severity="portability">Non reentrant function 'getgrgid' called. For threadsafe applications it is recommended to use the reentrant replacement function 'getgrgid_r'.</warn>
   </function>
+  <!-- https://man7.org/linux/man-pages/man3/getgrnam.3.html -->
+  <!-- int getgrnam_r(const char *restrict name, struct group *restrict grp, char *restrict buf, size_t buflen, struct group **restrict result); -->
+  <function name="getgrnam_r">
+    <returnValue type="int"/>
+    <use-retval/>
+    <noreturn>false</noreturn>
+    <leak-ignore/>
+    <arg nr="1" direction="in">
+      <not-null/>
+      <not-uninit/>
+      <not-bool/>
+    </arg>
+    <arg nr="2" direction="out">
+      <not-null/>
+    </arg>
+    <arg nr="3" direction="out">
+      <not-null/>
+      <minsize type="argvalue" arg="4"/>
+    </arg>
+    <arg nr="4" direction="in">
+      <not-uninit/>
+      <valid>0:</valid>
+    </arg>
+    <arg nr="5" direction="out">
+      <not-null/>
+    </arg>    
+  </function>
+  <!-- https://man7.org/linux/man-pages/man3/getgrnam.3.html -->
+  <!-- int getgrgid_r(gid_t gid, struct group *restrict grp, char *restrict buf, size_t buflen, struct group **restrict result); -->
+  <function name="getgrgid_r">
+    <returnValue type="int"/>
+    <use-retval/>
+    <noreturn>false</noreturn>
+    <leak-ignore/>
+    <arg nr="1" direction="in">
+      <not-null/>
+      <not-uninit/>
+      <not-bool/>
+    </arg>
+    <arg nr="2" direction="out">
+      <not-null/>
+    </arg>
+    <arg nr="3" direction="out">
+      <not-null/>
+      <minsize type="argvalue" arg="4"/>
+    </arg>
+    <arg nr="4" direction="in">
+      <not-uninit/>
+      <valid>0:</valid>
+    </arg>
+    <arg nr="5" direction="out">
+      <not-null/>
+    </arg>    
+  </function>                      
   <!-- char *getlogin(void); -->
   <function name="getlogin">
     <returnValue type="char *"/>
diff --git a/test/cfg/posix.c b/test/cfg/posix.c
index 07010c84b..826976c49 100644
--- a/test/cfg/posix.c
+++ b/test/cfg/posix.c
@@ -16,6 +16,7 @@
 #include <sys/sem.h>
 #include <sys/time.h>
 #include <sys/types.h>
+#include <grp.h>
 #include <dlfcn.h>
 #include <fcntl.h>
 // unavailable on some linux systems #include <ndbm.h>
@@ -33,6 +34,30 @@
 #include <string.h>
 #include <strings.h>
 
+int nullPointer_getgrgid_r(gid_t gid, struct group *restrict grp, char *restrict buf, size_t buflen, struct group **restrict result)
+{
+    // cppcheck-suppress nullPointer
+    (void) getgrgid_r(gid, NULL, buf, buflen, result);
+    // cppcheck-suppress nullPointer
+    (void) getgrgid_r(gid, grp, NULL, buflen, result);
+    // cppcheck-suppress nullPointer
+    (void) getgrgid_r(gid, grp, buf, buflen, NULL);
+    return getgrgid_r(gid, grp, buf, buflen, result);
+}
+
+int nullPointer_getgrnam_r(const char *restrict name, struct group *restrict grp, char *restrict buf, size_t buflen, struct group **restrict result)
+{
+    // cppcheck-suppress nullPointer
+    (void) getgrnam_r(NULL, grp, buf, buflen, result);
+    // cppcheck-suppress nullPointer
+    (void) getgrnam_r(name, NULL, buf, buflen, result);
+    // cppcheck-suppress nullPointer
+    (void) getgrnam_r(name, grp, NULL, buflen, result);
+    // cppcheck-suppress nullPointer
+    (void) getgrnam_r(name, grp, buf, buflen, NULL);
+    return getgrnam_r(name, grp, buf, buflen, result);
+}
+
 void knownConditionTrueFalse_ffs(int i)
 {
     // ffs() returns the position of the first bit set, or 0 if no bits are set in i.