diff --git a/common/jpeg/acinclude.m4 b/common/jpeg/acinclude.m4
index f7d7b69..9b8d312 100644
--- a/common/jpeg/acinclude.m4
+++ b/common/jpeg/acinclude.m4
@@ -44,7 +44,14 @@
     objfmt='ELF'
   ;;
   darwin* | rhapsody* | nextstep* | openstep* | macos*)
-    objfmt='Mach-O'
+    case "$host_cpu" in
+      x86_64)
+        objfmt='Mach-O64'
+        ;;
+      *)
+        objfmt='Mach-O'
+        ;;
+    esac
   ;;
   *)
     objfmt='ELF ?'
@@ -68,6 +75,7 @@
   ELF64)      NAFLAGS='-felf64 -DELF -D__x86_64__';;
   RDF)        NAFLAGS='-frdf -DRDF';;
   Mach-O)     NAFLAGS='-fmacho -DMACHO';;
+  Mach-O64)   NAFLAGS='-fmacho64 -DMACHO -D__x86_64__';;
 esac
 AC_MSG_RESULT([$NAFLAGS])
 AC_SUBST([NAFLAGS])
diff --git a/common/jpeg/simd/jsimd_x86_64.c b/common/jpeg/simd/jsimd_x86_64.c
index 4c1ef7d..0da564c 100644
--- a/common/jpeg/simd/jsimd_x86_64.c
+++ b/common/jpeg/simd/jsimd_x86_64.c
@@ -24,7 +24,7 @@
  * In the PIC cases, we have no guarantee that constants will keep
  * their alignment. This macro allows us to verify it at runtime.
  */
-#define IS_ALIGNED(ptr, order) (((unsigned)ptr & ((1 << order) - 1)) == 0)
+#define IS_ALIGNED(ptr, order) (((unsigned long)ptr & ((1 << order) - 1)) == 0)
 
 #define IS_ALIGNED_SSE(ptr) (IS_ALIGNED(ptr, 4)) /* 16 byte alignment */
 
diff --git a/common/jpeg/simd/nasm_lt.sh b/common/jpeg/simd/nasm_lt.sh
index 68893b7..b112862 100755
--- a/common/jpeg/simd/nasm_lt.sh
+++ b/common/jpeg/simd/nasm_lt.sh
@@ -12,7 +12,7 @@
             fi
             ;;
         -f|-fbin|-faout|-faoutb|-fcoff|-felf|-felf64|-fas86| \
-        -fobj|-fwin32|-frdf|-fieee|-fmacho)
+        -fobj|-fwin32|-frdf|-fieee|-fmacho|-fmacho64)
             # it's a file format specifier for nasm.
             command="$command $1"
             ;;