diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index b74aa4d44c..5506c933de 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -258,7 +258,7 @@ static bool print_type_number(Visitor *v, const char *name, double *obj,
                               Error **errp)
 {
     StringOutputVisitor *sov = to_sov(v);
-    string_output_set(sov, g_strdup_printf("%f", *obj));
+    string_output_set(sov, g_strdup_printf("%.17g", *obj));
     return true;
 }
 
diff --git a/tests/test-string-output-visitor.c b/tests/test-string-output-visitor.c
index cec20848ea..0dae04b960 100644
--- a/tests/test-string-output-visitor.c
+++ b/tests/test-string-output-visitor.c
@@ -136,7 +136,7 @@ static void test_visitor_out_number(TestOutputVisitorData *data,
     visit_type_number(data->ov, NULL, &value, &error_abort);
 
     str = visitor_get(data);
-    g_assert_cmpstr(str, ==, "3.141593");
+    g_assert_cmpstr(str, ==, "3.1415926535897931");
 }
 
 static void test_visitor_out_string(TestOutputVisitorData *data,