diff --git a/src/msg.cpp b/src/msg.cpp
index 906443cf..fa38d6d5 100644
--- a/src/msg.cpp
+++ b/src/msg.cpp
@@ -80,7 +80,7 @@ int zmq::msg_t::init_data (void *data_, size_t size_, msg_free_fn *ffn_,
 {
     //  If data is NULL and size is not 0, a segfault
     //  would occur once the data is accessed
-    assert (data_ != NULL || size_ == 0);
+    zmq_assert (data_ != NULL || size_ == 0);
     
     file_desc = -1;
 
diff --git a/src/proxy.cpp b/src/proxy.cpp
index 90658d55..5ef11ab9 100644
--- a/src/proxy.cpp
+++ b/src/proxy.cpp
@@ -125,7 +125,7 @@ int zmq::proxy (
             else {
                 //  This is an API error, we should assert
                 puts ("E: invalid command sent to proxy");
-                assert (false);
+                zmq_assert (false);
             }
         }
         //  Process a request
diff --git a/src/req.cpp b/src/req.cpp
index 4c510526..5c1e63ea 100644
--- a/src/req.cpp
+++ b/src/req.cpp
@@ -81,7 +81,7 @@ int zmq::req_t::xsend (msg_t *msg_)
         rc = dealer_t::sendpipe (&bottom, &reply_pipe);
         if (rc != 0)
             return -1;
-        assert (reply_pipe);
+        zmq_assert (reply_pipe);
 
         message_begins = false;
 
diff --git a/src/stream_engine.cpp b/src/stream_engine.cpp
index 3f0774bb..20d8f395 100644
--- a/src/stream_engine.cpp
+++ b/src/stream_engine.cpp
@@ -217,7 +217,7 @@ void zmq::stream_engine_t::terminate ()
 
 void zmq::stream_engine_t::in_event ()
 {
-    assert (!io_error);
+    zmq_assert (!io_error);
 
     //  If still handshaking, receive and process the greeting message.
     if (unlikely (handshaking))