diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index 47732aba7b..ba31cccc6f 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -2879,6 +2879,8 @@ int qemudBuildCommandLine(virConnectPtr conn,
         qenv[qenvc++] = envval;                                         \
     } while (0)
 
+    /* Make sure to unset or set all envvars in qemuxml2argvtest.c that
+     * are copied here using this macro, otherwise the test may fail */
 #define ADD_ENV_COPY(envname)                                           \
     do {                                                                \
         char *val = getenv(envname);                                    \
diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
index 41e5749fb0..fc237c2124 100644
--- a/tests/qemuxml2argvtest.c
+++ b/tests/qemuxml2argvtest.c
@@ -184,6 +184,9 @@ mymain(int argc, char **argv)
 #define DO_TEST(name, extraFlags)                       \
         DO_TEST_FULL(name, extraFlags, NULL)
 
+    /* Unset or set all envvars here that are copied in qemudBuildCommandLine
+     * using ADD_ENV_COPY, otherwise these tests may fail due to unexpected
+     * values for these envvars */
     setenv("PATH", "/bin", 1);
     setenv("USER", "test", 1);
     setenv("LOGNAME", "test", 1);
@@ -191,6 +194,8 @@ mymain(int argc, char **argv)
     unsetenv("TMPDIR");
     unsetenv("LD_PRELOAD");
     unsetenv("LD_LIBRARY_PATH");
+    unsetenv("QEMU_AUDIO_DRV");
+    unsetenv("SDL_AUDIODRIVER");
 
     DO_TEST("minimal", QEMUD_CMD_FLAG_NAME);
     DO_TEST("machine-aliases1", 0);