diff --git a/grpc-sys/grpc_wrap.cc b/grpc-sys/grpc_wrap.cc
index e37872a9..1975d43c 100644
--- a/grpc-sys/grpc_wrap.cc
+++ b/grpc-sys/grpc_wrap.cc
@@ -66,6 +66,11 @@
 #define GPR_CALLTYPE
 #endif
 
+#ifndef GPR_ASSERT
+#include <assert.h>
+#define GPR_ASSERT assert
+#endif
+
 grpc_byte_buffer* string_to_byte_buffer(const char* buffer, size_t len) {
   grpc_slice slice = grpc_slice_from_copied_buffer(buffer, len);
   grpc_byte_buffer* bb = grpc_raw_byte_buffer_create(&slice, 1);