diff --git a/src/ssh.c b/src/ssh.c
index 57089ec95..81627fe8b 100644
--- a/src/ssh.c
+++ b/src/ssh.c
@@ -258,10 +258,13 @@ WS_SOCKET_T wolfSSH_get_fd(const WOLFSSH* ssh)
     if (ssh)
         return ssh->rfd;
 
+    /* Return the same invalid-socket sentinel wolfSSH_new() initializes
+     * rfd/wfd to, rather than an error enum, so callers get a value of the
+     * socket type they can compare against. */
 #ifdef USE_WINDOWS_API
     return INVALID_SOCKET;
 #else
-    return WS_BAD_ARGUMENT;
+    return -1;
 #endif
 }
 
diff --git a/tests/api.c b/tests/api.c
index 55009434c..5635e2a5a 100644
--- a/tests/api.c
+++ b/tests/api.c
@@ -238,7 +238,11 @@ static void test_wolfSSH_set_fd(void)
 
     AssertIntNE(WS_SUCCESS, wolfSSH_set_fd(NULL, fd));
     check = wolfSSH_get_fd(NULL);
-    AssertFalse(WS_SUCCESS == check);
+#ifdef USE_WINDOWS_API
+    AssertTrue(INVALID_SOCKET == check);
+#else
+    AssertTrue(-1 == check);
+#endif
 
     AssertIntEQ(WS_SUCCESS, wolfSSH_set_fd(ssh, fd));
     check = wolfSSH_get_fd(ssh);