diff --git a/tools/toolchains/__init__.py b/tools/toolchains/__init__.py
index 4dcc59b5c7..845312b8df 100644
--- a/tools/toolchains/__init__.py
+++ b/tools/toolchains/__init__.py
@@ -217,7 +217,7 @@ class mbedToolchain:
 
         self.mp_pool = None
         
-        if 'UVISOR_PRESENT' in self.macros:
+        if 'UVISOR_PRESENT=1' in self.macros:
             self.target.core = re.sub(r"F$", '', self.target.core)
 
     def get_output(self):