diff --git a/components/esp_modem/include/generate/esp_modem_command_declare_helper.inc b/components/esp_modem/include/generate/esp_modem_command_declare_helper.inc
index 2d2cec90db..fb64bc80d9 100644
--- a/components/esp_modem/include/generate/esp_modem_command_declare_helper.inc
+++ b/components/esp_modem/include/generate/esp_modem_command_declare_helper.inc
@@ -3,9 +3,9 @@
 // Parameters
 // * handle different parameters for C++ and C API
 // * make parameter unique names, so they could be easily referenced and forwarded
-#define _ARG(param, name) param
 #define INT_IN(param, name) int  _ARG(param, name)
 #ifdef __cplusplus
+#define _ARG(param, name) param
 #include <string>
 #define STRING_IN(param, name) const std::string& _ARG(param, name)
 #define STRING_OUT(param, name) std::string& _ARG(param, name)
@@ -16,6 +16,7 @@
 
 #define STRUCT_OUT(struct_name, p1)  struct_name& p1
 #else
+#define _ARG(param, name) name
 #define STRING_IN(param, name) const char* _ARG(param, name)
 #define STRING_OUT(param, name) char* _ARG(param, name)
 #define BOOL_IN(param, name) const bool _ARG(param, name)