diff --git a/src/configure b/src/configure
index a9b7567fd6..9a2e8798ae 100755
--- a/src/configure
+++ b/src/configure
@@ -5935,7 +5935,13 @@ case $OS in
       LDFLAGS="$LDFLAGS -isysroot ${enable_sdk} -mmacosx-version-min=10.4"
     fi
 
-    enable_futures_by_default=yes
+    case `$UNAME -m` in
+      i386)
+       enable_futures_by_default=yes
+       ;;
+      *)
+       ;;
+    esac
 
     PREFLAGS="$PREFLAGS -DOS_X -D_DARWIN_UNLIMITED_SELECT"
 
diff --git a/src/mzscheme/configure.ac b/src/mzscheme/configure.ac
index c868c6a7f0..354e16487f 100644
--- a/src/mzscheme/configure.ac
+++ b/src/mzscheme/configure.ac
@@ -645,7 +645,13 @@ case $OS in
       LDFLAGS="$LDFLAGS -isysroot ${enable_sdk} -mmacosx-version-min=10.4"
     fi
     
-    enable_futures_by_default=yes
+    case `$UNAME -m` in
+      i386)
+       enable_futures_by_default=yes
+       ;;
+      *)
+       ;;
+    esac
 
     PREFLAGS="$PREFLAGS -DOS_X -D_DARWIN_UNLIMITED_SELECT"