diff --git a/libraries/AP_Common/tests/test_nmea_print.cpp b/libraries/AP_Common/tests/test_nmea_print.cpp
index 1ce98138c1..85bc0a886d 100644
--- a/libraries/AP_Common/tests/test_nmea_print.cpp
+++ b/libraries/AP_Common/tests/test_nmea_print.cpp
@@ -31,15 +31,12 @@ static DummyUart test_uart;
 
 TEST(NMEA, Printf)
 {
-    EXPECT_FALSE(nmea_printf(&test_uart, ""));
-    char test_string[] = "test\n";  // blabla not an NMEA string but whatever
-    const size_t len = strlen(test_string);
     // test not enought space
-    test_uart.set_txspace(len-2);
-    EXPECT_FALSE(nmea_printf(&test_uart, test_string));
+    test_uart.set_txspace(2);
+    EXPECT_FALSE(nmea_printf(&test_uart, "TEST"));
     // normal test
-    test_uart.set_txspace(42);
-    EXPECT_TRUE(nmea_printf(&test_uart, test_string));
+    test_uart.set_txspace(9);
+    EXPECT_TRUE(nmea_printf(&test_uart, "TEST"));
 }
 
 AP_GTEST_MAIN()