diff --git a/tests/unit/test-cutils.c b/tests/unit/test-cutils.c
index 4a1baf05ca6..1272638582a 100644
--- a/tests/unit/test-cutils.c
+++ b/tests/unit/test-cutils.c
@@ -310,7 +310,7 @@ static void test_qemu_strtoi_null(void)
     err = qemu_strtoi(NULL, &endptr, 0, &res);

     g_assert_cmpint(err, ==, -EINVAL);
-    g_assert_cmpint(res, ==, 999);
+    g_assert_cmpint(res, ==, 0);
     g_assert_null(endptr);
 }

@@ -610,7 +610,7 @@ static void test_qemu_strtoi_full_null(void)
     err = qemu_strtoi(NULL, &endptr, 0, &res);

     g_assert_cmpint(err, ==, -EINVAL);
-    g_assert_cmpint(res, ==, 999);
+    g_assert_cmpint(res, ==, 0);
     g_assert_null(endptr);
 }

@@ -713,7 +713,7 @@ static void test_qemu_strtoui_null(void)
     err = qemu_strtoui(NULL, &endptr, 0, &res);

     g_assert_cmpint(err, ==, -EINVAL);
-    g_assert_cmpuint(res, ==, 999);
+    g_assert_cmpuint(res, ==, 0);
     g_assert_null(endptr);
 }

@@ -1011,7 +1011,7 @@ static void test_qemu_strtoui_full_null(void)
     err = qemu_strtoui(NULL, NULL, 0, &res);

     g_assert_cmpint(err, ==, -EINVAL);
-    g_assert_cmpuint(res, ==, 999);
+    g_assert_cmpuint(res, ==, 0);
 }

 static void test_qemu_strtoui_full_empty(void)
@@ -1111,7 +1111,7 @@ static void test_qemu_strtol_null(void)
     err = qemu_strtol(NULL, &endptr, 0, &res);

     g_assert_cmpint(err, ==, -EINVAL);
-    g_assert_cmpint(res, ==, 999);
+    g_assert_cmpint(res, ==, 0);
     g_assert_null(endptr);
 }

@@ -1415,7 +1415,7 @@ static void test_qemu_strtol_full_null(void)
     err = qemu_strtol(NULL, &endptr, 0, &res);

     g_assert_cmpint(err, ==, -EINVAL);
-    g_assert_cmpint(res, ==, 999);
+    g_assert_cmpint(res, ==, 0);
     g_assert_null(endptr);
 }

@@ -1518,7 +1518,7 @@ static void test_qemu_strtoul_null(void)
     err = qemu_strtoul(NULL, &endptr, 0, &res);

     g_assert_cmpint(err, ==, -EINVAL);
-    g_assert_cmpuint(res, ==, 999);
+    g_assert_cmpuint(res, ==, 0);
     g_assert_null(endptr);
 }

@@ -1811,7 +1811,7 @@ static void test_qemu_strtoul_full_null(void)
     err = qemu_strtoul(NULL, NULL, 0, &res);

     g_assert_cmpint(err, ==, -EINVAL);
-    g_assert_cmpuint(res, ==, 999);
+    g_assert_cmpuint(res, ==, 0);
 }

 static void test_qemu_strtoul_full_empty(void)
@@ -1911,7 +1911,7 @@ static void test_qemu_strtoi64_null(void)
     err = qemu_strtoi64(NULL, &endptr, 0, &res);

     g_assert_cmpint(err, ==, -EINVAL);
-    g_assert_cmpint(res, ==, 999);
+    g_assert_cmpint(res, ==, 0);
     g_assert_null(endptr);
 }

@@ -2201,7 +2201,7 @@ static void test_qemu_strtoi64_full_null(void)
     err = qemu_strtoi64(NULL, NULL, 0, &res);

     g_assert_cmpint(err, ==, -EINVAL);
-    g_assert_cmpint(res, ==, 999);
+    g_assert_cmpint(res, ==, 0);
 }

 static void test_qemu_strtoi64_full_empty(void)
@@ -2304,7 +2304,7 @@ static void test_qemu_strtou64_null(void)
     err = qemu_strtou64(NULL, &endptr, 0, &res);

     g_assert_cmpint(err, ==, -EINVAL);
-    g_assert_cmpuint(res, ==, 999);
+    g_assert_cmpuint(res, ==, 0);
     g_assert_null(endptr);
 }

@@ -2593,7 +2593,7 @@ static void test_qemu_strtou64_full_null(void)
     err = qemu_strtou64(NULL, NULL, 0, &res);

     g_assert_cmpint(err, ==, -EINVAL);
-    g_assert_cmpuint(res, ==, 999);
+    g_assert_cmpuint(res, ==, 0);
 }

 static void test_qemu_strtou64_full_empty(void)
diff --git a/util/cutils.c b/util/cutils.c
index 24955d3ca94..b5a6641fa0f 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -384,12 +384,13 @@ static int check_strtox_error(const char *nptr, char *ep,
  *
  * @nptr may be null, and no conversion is performed then.
  *
- * If no conversion is performed, store @nptr in *@endptr and return
- * -EINVAL.
+ * If no conversion is performed, store @nptr in *@endptr, 0 in
+ * @result, and return -EINVAL.
  *
  * If @endptr is null, and the string isn't fully converted, return
- * -EINVAL.  This is the case when the pointer that would be stored in
- * a non-null @endptr points to a character other than '\0'.
+ * -EINVAL with @result set to the parsed value.  This is the case
+ * when the pointer that would be stored in a non-null @endptr points
+ * to a character other than '\0'.
  *
  * If the conversion overflows @result, store INT_MAX in @result,
  * and return -ERANGE.
@@ -407,6 +408,7 @@ int qemu_strtoi(const char *nptr, const char **endptr, int base,

     assert((unsigned) base <= 36 && base != 1);
     if (!nptr) {
+        *result = 0;
         if (endptr) {
             *endptr = nptr;
         }
@@ -436,12 +438,13 @@ int qemu_strtoi(const char *nptr, const char **endptr, int base,
  *
  * @nptr may be null, and no conversion is performed then.
  *
- * If no conversion is performed, store @nptr in *@endptr and return
- * -EINVAL.
+ * If no conversion is performed, store @nptr in *@endptr, 0 in
+ * @result, and return -EINVAL.
  *
  * If @endptr is null, and the string isn't fully converted, return
- * -EINVAL.  This is the case when the pointer that would be stored in
- * a non-null @endptr points to a character other than '\0'.
+ * -EINVAL with @result set to the parsed value.  This is the case
+ * when the pointer that would be stored in a non-null @endptr points
+ * to a character other than '\0'.
  *
  * If the conversion overflows @result, store UINT_MAX in @result,
  * and return -ERANGE.
@@ -460,6 +463,7 @@ int qemu_strtoui(const char *nptr, const char **endptr, int base,

     assert((unsigned) base <= 36 && base != 1);
     if (!nptr) {
+        *result = 0;
         if (endptr) {
             *endptr = nptr;
         }
@@ -501,12 +505,13 @@ int qemu_strtoui(const char *nptr, const char **endptr, int base,
  *
  * @nptr may be null, and no conversion is performed then.
  *
- * If no conversion is performed, store @nptr in *@endptr and return
- * -EINVAL.
+ * If no conversion is performed, store @nptr in *@endptr, 0 in
+ * @result, and return -EINVAL.
  *
  * If @endptr is null, and the string isn't fully converted, return
- * -EINVAL.  This is the case when the pointer that would be stored in
- * a non-null @endptr points to a character other than '\0'.
+ * -EINVAL with @result set to the parsed value.  This is the case
+ * when the pointer that would be stored in a non-null @endptr points
+ * to a character other than '\0'.
  *
  * If the conversion overflows @result, store LONG_MAX in @result,
  * and return -ERANGE.
@@ -523,6 +528,7 @@ int qemu_strtol(const char *nptr, const char **endptr, int base,

     assert((unsigned) base <= 36 && base != 1);
     if (!nptr) {
+        *result = 0;
         if (endptr) {
             *endptr = nptr;
         }
@@ -543,12 +549,13 @@ int qemu_strtol(const char *nptr, const char **endptr, int base,
  *
  * @nptr may be null, and no conversion is performed then.
  *
- * If no conversion is performed, store @nptr in *@endptr and return
- * -EINVAL.
+ * If no conversion is performed, store @nptr in *@endptr, 0 in
+ * @result, and return -EINVAL.
  *
  * If @endptr is null, and the string isn't fully converted, return
- * -EINVAL.  This is the case when the pointer that would be stored in
- * a non-null @endptr points to a character other than '\0'.
+ * -EINVAL with @result set to the parsed value.  This is the case
+ * when the pointer that would be stored in a non-null @endptr points
+ * to a character other than '\0'.
  *
  * If the conversion overflows @result, store ULONG_MAX in @result,
  * and return -ERANGE.
@@ -566,6 +573,7 @@ int qemu_strtoul(const char *nptr, const char **endptr, int base,

     assert((unsigned) base <= 36 && base != 1);
     if (!nptr) {
+        *result = 0;
         if (endptr) {
             *endptr = nptr;
         }
@@ -594,6 +602,7 @@ int qemu_strtoi64(const char *nptr, const char **endptr, int base,

     assert((unsigned) base <= 36 && base != 1);
     if (!nptr) {
+        *result = 0;
         if (endptr) {
             *endptr = nptr;
         }
@@ -621,6 +630,7 @@ int qemu_strtou64(const char *nptr, const char **endptr, int base,

     assert((unsigned) base <= 36 && base != 1);
     if (!nptr) {
+        *result = 0;
         if (endptr) {
             *endptr = nptr;
         }
