diff --git a/src/foreign/foreign.c b/src/foreign/foreign.c
index 1e8faa6658..b782eebfcb 100644
--- a/src/foreign/foreign.c
+++ b/src/foreign/foreign.c
@@ -2448,7 +2448,7 @@ Scheme_Object *ffi_do_call(void *data, int argc, Scheme_Object *argv[])
   } else {
     ivals   = malloc(nargs * sizeof(ForeignAny));
     avalues = scheme_malloc(nargs * sizeof(void*));
-    offsets = scheme_malloc(nargs * sizeof(long));
+    offsets = scheme_malloc_atomic(nargs * sizeof(long));
   }
   /* iterate on input values and types */
   for (i=0; i<nargs; i++, itypes=SCHEME_CDR(itypes)) {
diff --git a/src/foreign/foreign.ssc b/src/foreign/foreign.ssc
index cb2da8b6b4..46197850b1 100755
--- a/src/foreign/foreign.ssc
+++ b/src/foreign/foreign.ssc
@@ -1818,7 +1818,7 @@ Scheme_Object *ffi_do_call(void *data, int argc, Scheme_Object *argv[])
   } else {
     ivals   = malloc(nargs * sizeof(ForeignAny));
     avalues = scheme_malloc(nargs * sizeof(void*));
-    offsets = scheme_malloc(nargs * sizeof(long));
+    offsets = scheme_malloc_atomic(nargs * sizeof(long));
   }
   /* iterate on input values and types */
   for (i=0; i<nargs; i++, itypes=SCHEME_CDR(itypes)) {