diff --git a/include/qemu/option.h b/include/qemu/option.h
index 7a58e477d9..63db4ccb9a 100644
--- a/include/qemu/option.h
+++ b/include/qemu/option.h
@@ -46,6 +46,7 @@ typedef struct QEMUOptionParameter {
         char* s;
     } value;
     const char *help;
+    bool assigned;
 } QEMUOptionParameter;
 
 
diff --git a/util/qemu-option.c b/util/qemu-option.c
index 4ebdc4c33c..e0844a966c 100644
--- a/util/qemu-option.c
+++ b/util/qemu-option.c
@@ -275,6 +275,8 @@ int set_option_parameter(QEMUOptionParameter *list, const char *name,
         return -1;
     }
 
+    list->assigned = true;
+
     return 0;
 }
 
@@ -306,6 +308,8 @@ int set_option_parameter_int(QEMUOptionParameter *list, const char *name,
         return -1;
     }
 
+    list->assigned = true;
+
     return 0;
 }
 
@@ -397,6 +401,7 @@ QEMUOptionParameter *parse_option_parameters(const char *param,
     char value[256];
     char *param_delim, *value_delim;
     char next_delim;
+    int i;
 
     if (list == NULL) {
         return NULL;
@@ -406,6 +411,10 @@ QEMUOptionParameter *parse_option_parameters(const char *param,
         dest = allocated = append_option_parameters(NULL, list);
     }
 
+    for (i = 0; dest[i].name; i++) {
+        dest[i].assigned = false;
+    }
+
     while (*param) {
 
         // Find parameter name and value in the string