--- Source/WTF/wtf/FastMalloc.cpp
+++ Source/WTF/wtf/FastMalloc.cpp
@@ -93,6 +93,10 @@
 #include <malloc/malloc.h>
 #endif
 
+#if OS(DARWIN) && CPU(ARM64)
+#include <arm/param.h>
+#endif
+
 #ifndef NO_TCMALLOC_SAMPLES
 #ifdef WTF_CHANGES
 #define NO_TCMALLOC_SAMPLES
@@ -628,7 +632,13 @@
 // sense.  In particular, if kMaxSize increases, you may have to
 // increase kNumClasses as well.
 #if OS(DARWIN)
-#    define K_PAGE_SHIFT PAGE_SHIFT
+#    if CPU(X86_64)
+#        define K_PAGE_SHIFT I386_PGSHIFT
+#    elif CPU(ARM64)
+#        define K_PAGE_SHIFT PGSHIFT
+#    else
+#        define K_PAGE_SHIFT PAGE_SHIFT
+#    endif
 #    if (K_PAGE_SHIFT == 12)
 #        define K_NUM_CLASSES 68
 #    elif (K_PAGE_SHIFT == 14)