diff --git a/qemu/qapi/string-input-visitor.c b/qemu/qapi/string-input-visitor.c
index 0cdc32ca..4dbff4bf 100644
--- a/qemu/qapi/string-input-visitor.c
+++ b/qemu/qapi/string-input-visitor.c
@@ -182,12 +182,6 @@ static void parse_type_int64(Visitor *v, const char *name, int64_t *obj,
 {
     StringInputVisitor *siv = to_siv(v);
 
-    if (!siv->string) {
-        error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
-                   "integer");
-        return;
-    }
-
     if (parse_str(siv, name, errp) < 0) {
         return;
     }
@@ -240,19 +234,17 @@ static void parse_type_bool(Visitor *v, const char *name, bool *obj,
 {
     StringInputVisitor *siv = to_siv(v);
 
-    if (siv->string) {
-        if (!strcasecmp(siv->string, "on") ||
-            !strcasecmp(siv->string, "yes") ||
-            !strcasecmp(siv->string, "true")) {
-            *obj = true;
-            return;
-        }
-        if (!strcasecmp(siv->string, "off") ||
-            !strcasecmp(siv->string, "no") ||
-            !strcasecmp(siv->string, "false")) {
-            *obj = false;
-            return;
-        }
+    if (!strcasecmp(siv->string, "on") ||
+        !strcasecmp(siv->string, "yes") ||
+        !strcasecmp(siv->string, "true")) {
+        *obj = true;
+        return;
+    }
+    if (!strcasecmp(siv->string, "off") ||
+        !strcasecmp(siv->string, "no") ||
+        !strcasecmp(siv->string, "false")) {
+        *obj = false;
+        return;
     }
 
     error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
@@ -263,13 +255,8 @@ static void parse_type_str(Visitor *v, const char *name, char **obj,
                            Error **errp)
 {
     StringInputVisitor *siv = to_siv(v);
-    if (siv->string) {
-        *obj = g_strdup(siv->string);
-    } else {
-        *obj = NULL;
-        error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
-                   "string");
-    }
+
+    *obj = g_strdup(siv->string);
 }
 
 static void parse_type_number(Visitor *v,  const char *name, double *obj,
@@ -280,10 +267,8 @@ static void parse_type_number(Visitor *v,  const char *name, double *obj,
     double val;
 
     errno = 0;
-    if (siv->string) {
-        val = strtod(siv->string, &endp);
-    }
-    if (!siv->string || errno || endp == siv->string || *endp) {
+    val = strtod(siv->string, &endp);
+    if (errno || endp == siv->string || *endp) {
         error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
                    "number");
         return;
@@ -305,6 +290,7 @@ Visitor *string_input_visitor_new(const char *str)
 {
     StringInputVisitor *v;
 
+    assert(str);
     v = g_malloc0(sizeof(*v));
 
     v->visitor.type = VISITOR_INPUT;