diff --git a/src/c/interpreter.d b/src/c/interpreter.d
index 7e9fdd205..bcf5668ad 100644
--- a/src/c/interpreter.d
+++ b/src/c/interpreter.d
@@ -26,35 +26,31 @@ void
 cl_stack_set_size(cl_index tentative_new_size)
 {
 	cl_index top = cl_env.stack_top - cl_env.stack;
-	cl_object *new_stack;
+	cl_object *new_stack, *old_stack;
 	cl_index safety_area = ecl_get_option(ECL_OPT_LISP_STACK_SAFETY_AREA);
 	cl_index new_size = tentative_new_size + 2*safety_area;
 
 	if (top > new_size)
 		FEerror("Internal error: cannot shrink stack that much.",0);
 
-	start_critical_section();
-
+	old_stack = cl_env.stack;
 	new_stack = (cl_object *)ecl_alloc_atomic(new_size * sizeof(cl_object));
-	memcpy(new_stack, cl_env.stack, cl_env.stack_size * sizeof(cl_object));
 
-#ifdef BOEHM_GBC
-	GC_free(cl_env.stack);
-#else
-	cl_dealloc(cl_env.stack);
-#endif
+	ecl_disable_interrupts();
+	memcpy(new_stack, old_stack, cl_env.stack_size * sizeof(cl_object));
 	cl_env.stack_size = new_size;
 	cl_env.stack = new_stack;
 	cl_env.stack_top = cl_env.stack + top;
 	cl_env.stack_limit = cl_env.stack + (new_size - 2*safety_area);
+	ecl_enable_interrupts();
+
+	cl_dealloc(old_stack);
 
 	/* A stack always has at least one element. This is assumed by cl__va_start
 	 * and friends, which take a sp=0 to have no arguments.
 	 */
 	if (top == 0)
 		cl_stack_push(MAKE_FIXNUM(0));
-
-	end_critical_section();
 }
 
 static void
diff --git a/src/c/stacks.d b/src/c/stacks.d
index 30f562bd7..33aecabde 100644
--- a/src/c/stacks.d
+++ b/src/c/stacks.d
@@ -171,7 +171,8 @@ bds_unwind_n(int n)
 static void
 bds_set_size(cl_index size)
 {
-	cl_index limit = (cl_env.bds_top - cl_env.bds_org);
+	bds_ptr old_org = cl_env.bds_org;
+	cl_index limit = cl_env.bds_top - old_org;
 	if (size <= limit) {
 		FEerror("Cannot shrink the binding stack below ~D.", 1,
 			ecl_make_unsigned_integer(limit));
@@ -179,11 +180,16 @@ bds_set_size(cl_index size)
 		cl_index margin = ecl_get_option(ECL_OPT_BIND_STACK_SAFETY_AREA);
 		bds_ptr org;
 		org = ecl_alloc_atomic(size * sizeof(*org));
-		memcpy(org, cl_env.bds_org, (limit + 1) * sizeof(*org));
+
+		ecl_disable_interrupts();
+		memcpy(org, old_org, (limit + 1) * sizeof(*org));
 		cl_env.bds_top = org + limit;
 		cl_env.bds_org = org;
 		cl_env.bds_limit = org + (size - 2*margin);
 		cl_env.bds_size = size;
+		ecl_enable_interrupts();
+
+		cl_dealloc(old_org);
 	}
 }
 
@@ -339,7 +345,8 @@ new_frame_id(void)
 static void
 frs_set_size(cl_index size)
 {
-	cl_index limit = (cl_env.frs_top - cl_env.frs_org);
+	ecl_frame_ptr old_org = cl_env.frs_top;
+	cl_index limit = cl_env.frs_top - old_org;
 	if (size <= limit) {
 		FEerror("Cannot shrink frame stack below ~D.", 1,
 			ecl_make_unsigned_integer(limit));
@@ -348,11 +355,16 @@ frs_set_size(cl_index size)
 		ecl_frame_ptr org;
 		size += 2*margin;
 		org = ecl_alloc_atomic(size * sizeof(*org));
-		memcpy(org, cl_env.frs_org, (limit + 1) * sizeof(*org));
+
+		ecl_disable_interrupts();
+		memcpy(org, old_org, (limit + 1) * sizeof(*org));
 		cl_env.frs_top = org + limit;
 		cl_env.frs_org = org;
 		cl_env.frs_limit = org + (size - 2*margin);
 		cl_env.frs_size = size;
+		ecl_enable_interrupts();
+
+		cl_dealloc(old_org);
 	}
 }