diff --git a/tools/toolchains/arm.py b/tools/toolchains/arm.py
index d3614e2c53..09b5524400 100644
--- a/tools/toolchains/arm.py
+++ b/tools/toolchains/arm.py
@@ -125,7 +125,7 @@ class ARM(mbedToolchain):
             })
 
     def _get_toolchain_labels(self):
-        if getattr(self.target, "default_lib", "std") == "small":
+        if getattr(self.target, "default_toolchain", "ARM") == "uARM":
             return ["ARM", "ARM_MICRO"]
         else:
             return ["ARM", "ARM_STD"]