diff --git a/examples/device/cdc_msc_freertos/Makefile b/examples/device/cdc_msc_freertos/Makefile
index 73b4ce608..5b5e513ad 100644
--- a/examples/device/cdc_msc_freertos/Makefile
+++ b/examples/device/cdc_msc_freertos/Makefile
@@ -37,10 +37,10 @@ SRC_S += \
 # CFLAGS += -Wno-error=sign-compare
 
 # Suppress FreeRTOSConfig.h warnings
-GCC_CFLAGS += -Wno-error=redundant-decls
+CFLAGS_GCC += -Wno-error=redundant-decls
 
 # Suppress FreeRTOS source warnings
-GCC_CFLAGS += -Wno-error=cast-qual
+CFLAGS_GCC += -Wno-error=cast-qual
 
 # FreeRTOS (lto + Os) linker issue
 LDFLAGS += -Wl,--undefined=vTaskSwitchContext
diff --git a/examples/device/hid_composite_freertos/Makefile b/examples/device/hid_composite_freertos/Makefile
index 9d30fddf7..cc1526cfe 100644
--- a/examples/device/hid_composite_freertos/Makefile
+++ b/examples/device/hid_composite_freertos/Makefile
@@ -36,10 +36,10 @@ SRC_S += \
 # CFLAGS += -Wno-error=sign-compare
 
 # Suppress FreeRTOSConfig.h warnings
-GCC_CFLAGS += -Wno-error=redundant-decls
+CFLAGS_GCC += -Wno-error=redundant-decls
 
 # Suppress FreeRTOS source warnings
-GCC_CFLAGS += -Wno-error=cast-qual
+CFLAGS_GCC += -Wno-error=cast-qual
 
 # FreeRTOS (lto + Os) linker issue
 LDFLAGS += -Wl,--undefined=vTaskSwitchContext
diff --git a/examples/device/net_lwip_webserver/Makefile b/examples/device/net_lwip_webserver/Makefile
index bc2914b36..90b429d00 100644
--- a/examples/device/net_lwip_webserver/Makefile
+++ b/examples/device/net_lwip_webserver/Makefile
@@ -3,7 +3,7 @@ DEPS_SUBMODULES += lib/lwip
 include ../../make.mk
 
 # suppress warning caused by lwip
-GCC_CFLAGS += \
+CFLAGS_GCC += \
   -Wno-error=null-dereference \
   -Wno-error=unused-parameter \
   -Wno-error=unused-variable