diff --git a/ports/atmel-samd/Makefile b/ports/atmel-samd/Makefile
index 31e69f36c9..ca906ab98f 100644
--- a/ports/atmel-samd/Makefile
+++ b/ports/atmel-samd/Makefile
@@ -104,19 +104,16 @@ else
   CFLAGS += -DNDEBUG
 
   # Do a default shrink for small builds, including all SAMD21 builds.
-  ifeq ($(CIRCUITPY_FULL_BUILD),0)
-    SHRINK_BUILD = 1
-  else
-    ifeq ($(CHIP_FAMILY), samd21)
-      SHRINK_BUILD = 1
-    endif
-  endif
-
   # -finline-limit can shrink the image size.
   # -finline-limit=80 or so is similar to not having it on.
   # There is no simple default value, though.
-  ifeq ($(SHRINK_BUILD), 1)
-    CFLAGS += -finline-limit=45 --param max-inline-insns-auto=110
+  ifeq ($(CIRCUITPY_FULL_BUILD),0)
+    CFLAGS += -finline-limit=45
+  else
+    ifeq ($(CHIP_FAMILY), samd21)
+      # max-inline-insns-auto increases the size of SAMD51 builds.
+      CFLAGS += -finline-limit=45 --param max-inline-insns-auto=110
+    endif
   endif
 
   # We used to do this but it seems to not reduce space any more, at least in gcc 11.