diff --git a/common/os_calls.c b/common/os_calls.c
index 1e4f6b1894..dd0122e153 100644
--- a/common/os_calls.c
+++ b/common/os_calls.c
@@ -3141,42 +3141,95 @@ g_getgroup_info(const char *groupname, int *gid)
 }
 
 /*****************************************************************************/
-/* returns error */
-/* if zero is returned, then ok is set */
-/* does not work in win32 */
+#ifdef HAVE_GETGROUPLIST
+int
+g_check_user_in_group(const char *username, int gid, int *ok)
+{
+    int rv = 1;
+    struct passwd *pwd_1 = getpwnam(username);
+    if (pwd_1 != NULL)
+    {
+        // Get number of groups for user
+        //
+        // Some implementations of getgrouplist() (i.e. muslc) don't
+        // allow ngroups to be <1 on entry
+        int ngroups = 1;
+        GETGROUPS_T dummy;
+        getgrouplist(username, pwd_1->pw_gid, &dummy, &ngroups);
+
+        if (ngroups > 0) // Should always be true
+        {
+            GETGROUPS_T *grouplist;
+            grouplist = (GETGROUPS_T *)malloc(ngroups * sizeof(grouplist[0]));
+            if (grouplist != NULL)
+            {
+                // Now get the actual groups. The number of groups returned
+                // by this call is not necessarily the same as the number
+                // returned by the first call.
+                int allocgroups = ngroups;
+                getgrouplist(username, pwd_1->pw_gid, grouplist, &ngroups);
+                ngroups = MIN(ngroups, allocgroups);
+
+                rv = 0;
+                *ok = 0;
+
+                int i;
+                for (i = 0 ; i < ngroups; ++i)
+                {
+                    if (grouplist[i] == (GETGROUPS_T)gid)
+                    {
+                        *ok = 1;
+                        break;
+                    }
+                }
+                free(grouplist);
+            }
+        }
+    }
+    return rv;
+}
+/*****************************************************************************/
+#else // HAVE_GETGROUPLIST
 int
 g_check_user_in_group(const char *username, int gid, int *ok)
 {
 #if defined(_WIN32)
     return 1;
 #else
-    struct group *groups;
     int i;
 
-    groups = getgrgid(gid);
-
-    if (groups == 0)
+    struct passwd *pwd_1 = getpwnam(username);
+    struct group *groups = getgrgid(gid);
+    if (pwd_1 == NULL || groups == NULL)
     {
         return 1;
     }
 
-    *ok = 0;
-    i = 0;
-
-    while (0 != groups->gr_mem[i])
+    if (pwd_1->pw_gid == gid)
     {
-        if (0 == g_strcmp(groups->gr_mem[i], username))
+        *ok = 1;
+    }
+    else
+    {
+        *ok = 0;
+        i = 0;
+
+        while (0 != groups->gr_mem[i])
         {
-            *ok = 1;
-            break;
-        }
+            if (0 == g_strcmp(groups->gr_mem[i], username))
+            {
+                *ok = 1;
+                break;
+            }
 
-        i++;
+            i++;
+        }
     }
 
     return 0;
 #endif
 }
+#endif // HAVE_GETGROUPLIST
 
 /*****************************************************************************/
 /* returns the time since the Epoch (00:00:00 UTC, January 1, 1970),
diff --git a/common/os_calls.h b/common/os_calls.h
index 5763019be4..5e8ebcc5e1 100644
--- a/common/os_calls.h
+++ b/common/os_calls.h
@@ -173,6 +173,15 @@ int      g_sigterm(int pid);
 int      g_getuser_info(const char *username, int *gid, int *uid, char **shell,
                         char **dir, char **gecos);
 int      g_getgroup_info(const char *groupname, int *gid);
+/**
+ * Checks whether a user is in the specified group
+ * @param username Name of user
+ * @param gid GID of group
+ * @param[out] ok Whether user is in group
+ * @return Non-zero if a system error occurred. In this instance OK is not set
+ *
+ * Primary group of username is also checked
+ */
 int      g_check_user_in_group(const char *username, int gid, int *ok);
 int      g_time1(void);
 int      g_time2(void);
diff --git a/configure.ac b/configure.ac
index 55131912c8..097424a4ef 100644
--- a/configure.ac
+++ b/configure.ac
@@ -189,6 +189,12 @@ AM_COND_IF([DEVEL_DEBUG],
   [AX_APPEND_COMPILE_FLAGS([-g -O0])],
   [AX_APPEND_COMPILE_FLAGS([-O2])])
 
+# Define HAVE_XXXXX macros for some system functions
+AC_CHECK_FUNCS([getgrouplist])
+
+# The type used by getgrouplist() is the same type used by getgroups()
+AC_TYPE_GETGROUPS
+
 # Don't fail without working nasm if rfxcodec is not enabled
 if test "x$enable_rfxcodec" != xyes; then
   with_simd=no
diff --git a/sesman/access.c b/sesman/access.c
index 442d9e7b4a..b70120bb9f 100644
--- a/sesman/access.c
+++ b/sesman/access.c
@@ -35,7 +35,6 @@
 int
 access_login_allowed(const char *user)
 {
-    int gid;
     int ok;
 
     if ((0 == g_strncmp(user, "root", 5)) && (0 == g_cfg->sec.allow_root))
@@ -51,18 +50,6 @@ access_login_allowed(const char *user)
         return 1;
     }
 
-    if (0 != g_getuser_info(user, &gid, 0, 0, 0, 0))
-    {
-        LOG(LOG_LEVEL_ERROR, "Cannot read user info! - login denied");
-        return 0;
-    }
-
-    if (g_cfg->sec.ts_users == gid)
-    {
-        LOG(LOG_LEVEL_DEBUG, "ts_users is user's primary group");
-        return 1;
-    }
-
     if (0 != g_check_user_in_group(user, g_cfg->sec.ts_users, &ok))
     {
         LOG(LOG_LEVEL_ERROR, "Cannot read group info! - login denied");
@@ -83,7 +70,6 @@ access_login_allowed(const char *user)
 int
 access_login_mng_allowed(const char *user)
 {
-    int gid;
     int ok;
 
     if ((0 == g_strncmp(user, "root", 5)) && (0 == g_cfg->sec.allow_root))
@@ -100,18 +86,6 @@ access_login_mng_allowed(const char *user)
         return 1;
     }
 
-    if (0 != g_getuser_info(user, &gid, 0, 0, 0, 0))
-    {
-        LOG(LOG_LEVEL_ERROR, "[MNG] Cannot read user info! - login denied");
-        return 0;
-    }
-
-    if (g_cfg->sec.ts_admins == gid)
-    {
-        LOG(LOG_LEVEL_INFO, "[MNG] ts_users is user's primary group");
-        return 1;
-    }
-
     if (0 != g_check_user_in_group(user, g_cfg->sec.ts_admins, &ok))
     {
         LOG(LOG_LEVEL_ERROR, "[MNG] Cannot read group info! - login denied");