diff --git a/ports/atmel-samd/mpconfigport.mk b/ports/atmel-samd/mpconfigport.mk
index e7aeb08058..c2eedfdc31 100644
--- a/ports/atmel-samd/mpconfigport.mk
+++ b/ports/atmel-samd/mpconfigport.mk
@@ -10,7 +10,7 @@ ifeq ($(LONGINT_IMPL),MPZ)
 MPY_TOOL_LONGINT_IMPL = -mlongint-impl=mpz
 endif
 
-ifeq ($(LONGINT_IMPL),LONGONG)
+ifeq ($(LONGINT_IMPL),LONGLONG)
 MPY_TOOL_LONGINT_IMPL = -mlongint-impl=longlong
 endif