diff --git a/lib/chibi/system.sld b/lib/chibi/system.sld
index e1b1faae..d0b64389 100644
--- a/lib/chibi/system.sld
+++ b/lib/chibi/system.sld
@@ -24,5 +24,5 @@
                      (getpwuid_r user (make-string 1024)))))
      (define (group-information group)
        (safe-car (if (string? group)
-                     (getgrnam_r group (make-string 1024))
-                     (getgrgid_r group (make-string 1024)))))))))
+                     (getgrnam-safe group (make-string 1024))
+                     (getgrgid-safe group (make-string 1024)))))))))
diff --git a/lib/chibi/system.stub b/lib/chibi/system.stub
index 1a99755b..15302f2f 100644
--- a/lib/chibi/system.stub
+++ b/lib/chibi/system.stub
@@ -83,15 +83,36 @@
 (cond-expand
   (emscripten)
   (else
-    (define-c errno getgrgid_r
-      (gid_t (result group)
+   (c-declare "
+    int getgrnam_safe(const char* name, struct group* grp,
+                      char* buf, size_t buflen,
+                      struct group** result) {
+      int res = getgrnam_r(name, grp, buf, buflen, result);
+      if (res == 0 && result == NULL) {
+        res = errno ? errno : ENOENT;
+      }
+      return res;
+    }
+    int getgrgid_safe(gid_t gid, struct group* grp,
+                      char* buf, size_t buflen,
+                      struct group** result) {
+      int res = getgrgid_r(gid, grp, buf, buflen, result);
+      if (res == 0 && result == NULL) {
+        res = errno ? errno : ENOENT;
+      }
+      return res;
+    }
+")
+
+   (define-c errno getgrgid-safe
+     (gid_t (result group)
+            (link string)
+            (value (string-size arg2) int)
+            (result pointer group)))
+
+   (define-c errno getgrnam-safe
+     (string (result group)
              (link string)
              (value (string-size arg2) int)
-             (result pointer group)))
-
-    (define-c errno getgrnam_r
-      (string (result group)
-              (link string)
-              (value (string-size arg2) int)
-              (result pointer group)))))
+             (result pointer group)))))