diff --git a/include/freerdp/settings.h b/include/freerdp/settings.h
index 4ffce003b..ed694e300 100644
--- a/include/freerdp/settings.h
+++ b/include/freerdp/settings.h
@@ -783,6 +783,7 @@ extern "C"
 	 * in case of an error.
 	 *  @since version 3.16.0
 	 */
+	WINPR_ATTR_MALLOC(free, 1)
 	FREERDP_API char* freerdp_settings_serialize(const rdpSettings* settings, BOOL pretty,
 	                                             size_t* plength);
 
diff --git a/winpr/include/winpr/json.h b/winpr/include/winpr/json.h
index d4b2f0eb6..de48124fc 100644
--- a/winpr/include/winpr/json.h
+++ b/winpr/include/winpr/json.h
@@ -401,6 +401,7 @@ extern "C"
 	 * @return A string representation of the JSON instance or \b NULL
 	 * @since version 3.6.0
 	 */
+	WINPR_ATTR_MALLOC(free, 1)
 	WINPR_API char* WINPR_JSON_Print(WINPR_JSON* item);
 
 	/**
@@ -411,6 +412,7 @@ extern "C"
 	 * @return A string representation of the JSON instance or \b NULL
 	 * @since version 3.6.0
 	 */
+	WINPR_ATTR_MALLOC(free, 1)
 	WINPR_API char* WINPR_JSON_PrintUnformatted(WINPR_JSON* item);
 
 #ifdef __cplusplus