diff --git a/src/ruby/ext/grpc/rb_grpc.c b/src/ruby/ext/grpc/rb_grpc.c
index 4b1015f..1cbd1aa 100644
--- a/src/ruby/ext/grpc/rb_grpc.c
+++ b/src/ruby/ext/grpc/rb_grpc.c
@@ -150,7 +150,7 @@
   return t;
 }
 
-void Init_grpc_status_codes() {
+static void Init_grpc_status_codes() {
   /* Constants representing the status codes or grpc_status_code in status.h */
   VALUE grpc_rb_mStatusCodes =
       rb_define_module_under(grpc_rb_mGrpcCore, "StatusCodes");
@@ -199,7 +199,7 @@
 static ID id_to_s;
 
 /* Converts a wrapped time constant to a standard time. */
-VALUE grpc_rb_time_val_to_time(VALUE self) {
+static VALUE grpc_rb_time_val_to_time(VALUE self) {
   gpr_timespec *time_const = NULL;
   Data_Get_Struct(self, gpr_timespec, time_const);
   return rb_funcall(rb_cTime, id_at, 2, INT2NUM(time_const->tv_sec),
@@ -207,17 +207,17 @@
 }
 
 /* Invokes inspect on the ctime version of the time val. */
-VALUE grpc_rb_time_val_inspect(VALUE self) {
+static VALUE grpc_rb_time_val_inspect(VALUE self) {
   return rb_funcall(grpc_rb_time_val_to_time(self), id_inspect, 0);
 }
 
 /* Invokes to_s on the ctime version of the time val. */
-VALUE grpc_rb_time_val_to_s(VALUE self) {
+static VALUE grpc_rb_time_val_to_s(VALUE self) {
   return rb_funcall(grpc_rb_time_val_to_time(self), id_to_s, 0);
 }
 
 /* Adds a module with constants that map to gpr's static timeval structs. */
-void Init_grpc_time_consts() {
+static void Init_grpc_time_consts() {
   VALUE grpc_rb_mTimeConsts =
       rb_define_module_under(grpc_rb_mGrpcCore, "TimeConsts");
   grpc_rb_cTimeVal =
@@ -244,7 +244,7 @@
   id_tv_nsec = rb_intern("tv_nsec");
 }
 
-void grpc_rb_shutdown(void *vm) { grpc_shutdown(); }
+static void grpc_rb_shutdown(void *vm) { grpc_shutdown(); }
 
 /* Initialize the GRPC module structs */