diff --git a/src/ctx.cpp b/src/ctx.cpp
index bd5f7f16..a1fbaa75 100644
--- a/src/ctx.cpp
+++ b/src/ctx.cpp
@@ -63,7 +63,7 @@
 #define ZMQ_CTX_TAG_VALUE_GOOD 0xabadcafe
 #define ZMQ_CTX_TAG_VALUE_BAD 0xdeadbeef
 
-int clipped_maxsocket (int max_requested_)
+static int clipped_maxsocket (int max_requested_)
 {
     if (max_requested_ >= zmq::poller_t::max_fds ()
         && zmq::poller_t::max_fds () != -1)
diff --git a/src/options.cpp b/src/options.cpp
index cc72190a..2b52621d 100644
--- a/src/options.cpp
+++ b/src/options.cpp
@@ -102,9 +102,9 @@ static int do_getsockopt_curve_key (void *const optval_,
 #endif
 
 template <typename T>
-int do_setsockopt (const void *const optval_,
-                   const size_t optvallen_,
-                   T *const out_value_)
+static int do_setsockopt (const void *const optval_,
+                          const size_t optvallen_,
+                          T *const out_value_)
 {
     if (optvallen_ == sizeof (T)) {
         memcpy (out_value_, optval_, sizeof (T));
@@ -176,9 +176,9 @@ do_setsockopt_string_allow_empty_relaxed (const void *const optval_,
 }
 
 template <typename T>
-int do_setsockopt_set (const void *const optval_,
-                       const size_t optvallen_,
-                       std::set<T> *const set_)
+static int do_setsockopt_set (const void *const optval_,
+                              const size_t optvallen_,
+                              std::set<T> *const set_)
 {
     if (optvallen_ == 0 && optval_ == NULL) {
         set_->clear ();
@@ -592,7 +592,7 @@ int zmq::options_t::setsockopt (int option_,
         case ZMQ_ZAP_DOMAIN:
             return do_setsockopt_string_allow_empty_relaxed (
               optval_, optvallen_, &zap_domain, UCHAR_MAX);
-            
+
             //  If curve encryption isn't built, these options provoke EINVAL
 #ifdef ZMQ_HAVE_CURVE
         case ZMQ_CURVE_SERVER:
diff --git a/src/proxy.cpp b/src/proxy.cpp
index d2bb43c9..338f52d6 100644
--- a/src/proxy.cpp
+++ b/src/proxy.cpp
@@ -89,9 +89,8 @@ typedef struct
 
 // Utility functions
 
-int capture (class zmq::socket_base_t *capture_,
-             zmq::msg_t *msg_,
-             int more_ = 0)
+static int
+capture (class zmq::socket_base_t *capture_, zmq::msg_t *msg_, int more_ = 0)
 {
     //  Copy message to capture socket if any
     if (capture_) {
@@ -109,12 +108,12 @@ int capture (class zmq::socket_base_t *capture_,
     return 0;
 }
 
-int forward (class zmq::socket_base_t *from_,
-             zmq_socket_stats_t *from_stats_,
-             class zmq::socket_base_t *to_,
-             zmq_socket_stats_t *to_stats_,
-             class zmq::socket_base_t *capture_,
-             zmq::msg_t *msg_)
+static int forward (class zmq::socket_base_t *from_,
+                    zmq_socket_stats_t *from_stats_,
+                    class zmq::socket_base_t *to_,
+                    zmq_socket_stats_t *to_stats_,
+                    class zmq::socket_base_t *capture_,
+                    zmq::msg_t *msg_)
 {
     // Forward a burst of messages
     for (unsigned int i = 0; i < zmq::proxy_burst_size; i++) {
@@ -184,9 +183,9 @@ static int loop_and_send_multipart_stat (zmq::socket_base_t *control_,
     return rc;
 }
 
-int reply_stats (class zmq::socket_base_t *control_,
-                 zmq_socket_stats_t *frontend_stats_,
-                 zmq_socket_stats_t *backend_stats_)
+static int reply_stats (class zmq::socket_base_t *control_,
+                        zmq_socket_stats_t *frontend_stats_,
+                        zmq_socket_stats_t *backend_stats_)
 {
     // first part: frontend stats - the first send might fail due to HWM
     if (loop_and_send_multipart_stat (control_, frontend_stats_->msg_in, true,
diff --git a/src/zmq.cpp b/src/zmq.cpp
index a33813d5..21895c10 100644
--- a/src/zmq.cpp
+++ b/src/zmq.cpp
@@ -726,7 +726,7 @@ const char *zmq_msg_gets (const zmq_msg_t *msg_, const char *property_)
 // Polling.
 
 #if defined ZMQ_HAVE_POLLER
-inline int zmq_poller_poll (zmq_pollitem_t *items_, int nitems_, long timeout_)
+static int zmq_poller_poll (zmq_pollitem_t *items_, int nitems_, long timeout_)
 {
     // implement zmq_poll on top of zmq_poller
     int rc;