diff --git a/src/configure b/src/configure
index 73b6dbd6a2..40d350e20b 100755
--- a/src/configure
+++ b/src/configure
@@ -10724,7 +10724,7 @@ fi
 ############### futures ###################
 
 if test "${enable_futures}" = "yes" ; then
-  PREFLAGS="$PREFLAGS -DFUTURES_ENABLED"
+  PREFLAGS="$PREFLAGS -DFUTURES_ENABLED -DUSE_PTHREAD_INSTEAD_OF_ITIMER"
   LDFLAGS="$LDFLAGS -pthread"
 fi
 
diff --git a/src/mzscheme/configure.ac b/src/mzscheme/configure.ac
index 3458707ad5..651acce180 100644
--- a/src/mzscheme/configure.ac
+++ b/src/mzscheme/configure.ac
@@ -1154,7 +1154,7 @@ fi
 ############### futures ###################
 
 if test "${enable_futures}" = "yes" ; then
-  PREFLAGS="$PREFLAGS -DFUTURES_ENABLED"
+  PREFLAGS="$PREFLAGS -DFUTURES_ENABLED -DUSE_PTHREAD_INSTEAD_OF_ITIMER"
   LDFLAGS="$LDFLAGS -pthread"
 fi