diff --git a/Make.inc b/Make.inc
index 8fb0eca..adeb33d 100644
--- a/Make.inc
+++ b/Make.inc
@@ -55,6 +55,9 @@ $(error "the mingw32 compiler you are using fails the openblas testsuite. please
 endif
 
 # OS-specific stuff
+ifeq ($(ARCH),arm64)
+override ARCH := aarch64
+endif
 ifeq ($(findstring arm,$(ARCH)),arm)
 override ARCH := arm
 MARCH ?= armv7-a
@@ -144,6 +147,16 @@ CFLAGS_add += -I$(OPENLIBM_HOME)/ld128
 endif
 endif
 
+ifneq ($(filter $(ARCH),i387 amd64),)
+# Determines whether `long double` is the same as `double` on this arch.
+# linux x86_64, for instance, `long double` is 80 bits wide, whereas on macOS aarch64,
+# `long double` is the same as `double`. 
+LONG_DOUBLE_NOT_DOUBLE := 1
+else ifeq ($(ARCH), aarch64)
+ifneq ($(OS),Darwin)
+LONG_DOUBLE_NOT_DOUBLE := 1
+endif
+endif
 
 %.c.o: %.c
 	$(CC) $(CPPFLAGS) $(CFLAGS) $(CFLAGS_add) -c $< -o $@
diff --git a/Makefile b/Makefile
index 2ffceb5..865123e 100644
--- a/Makefile
+++ b/Makefile
@@ -2,6 +2,7 @@ OPENLIBM_HOME=$(abspath .)
 include ./Make.inc
 
 SUBDIRS = src $(ARCH) bsdsrc
+ifeq ($(LONG_DOUBLE_NOT_DOUBLE),1)
 # Add ld80 directory on x86 and x64
 ifneq ($(filter $(ARCH),i387 amd64),)
 SUBDIRS += ld80
@@ -11,6 +12,7 @@ SUBDIRS += ld128
 else
 endif
 endif
+endif
 
 define INC_template
 TEST=test
diff --git a/src/Make.files b/src/Make.files
index 301bd2f..5170403 100644
--- a/src/Make.files
+++ b/src/Make.files
@@ -44,7 +44,7 @@ endif
 endif
 
 # Add in long double functions for x86, x64 and aarch64
-ifneq ($(filter $(ARCH),i387 amd64 aarch64),)
+ifeq ($(LONG_DOUBLE_NOT_DOUBLE),1)
 # C99 long double functions
 $(CUR_SRCS) +=	s_copysignl.c s_fabsl.c s_llrintl.c s_lrintl.c s_modfl.c