diff --git a/Changes b/Changes
index 2c5a606f9..55b980a8e 100644
--- a/Changes
+++ b/Changes
@@ -5,6 +5,8 @@ indicates the contributor was also the author of the fix; Thanks!
 
 * Verilator 3.871 devel
 
+***   Add VerilatedVcdFile to allow real-time waveforms, bug890. [HyungKi Jeong]
+
 ****  Fix comma-instantiations with parameters, bug884. [Franck Jullien]
 
 ****  Fix SystemC arrayed bit vectors, bug886. [David Poole]
diff --git a/include/verilated_vcd_c.cpp b/include/verilated_vcd_c.cpp
index 04c6cf376..528df83aa 100644
--- a/include/verilated_vcd_c.cpp
+++ b/include/verilated_vcd_c.cpp
@@ -76,11 +76,48 @@ protected:
 	: m_initcb(icb), m_fullcb(fcb), m_changecb(changecb), m_userthis(ut), m_code(code) {};
 };
 
+//=============================================================================
+//=============================================================================
+//=============================================================================
+// VerilatedVcdFile
+
+bool VerilatedVcdFile::open(const string& name) {
+    m_fd = ::open(name.c_str(), O_CREAT|O_WRONLY|O_TRUNC|O_LARGEFILE|O_NONBLOCK, 0666);
+    return (m_fd>=0);
+}
+
+void VerilatedVcdFile::close() {
+    ::close(m_fd);
+}
+
+ssize_t VerilatedVcdFile::write(const char* bufp, ssize_t len) {
+    return ::write(m_fd, bufp, len);
+}
+
 //=============================================================================
 //=============================================================================
 //=============================================================================
 // Opening/Closing
 
+VerilatedVcd::VerilatedVcd(VerilatedVcdFile* filep)
+    : m_isOpen(false), m_rolloverMB(0), m_modDepth(0), m_nextCode(1) {
+    // Not in header to avoid link issue if header is included without this .cpp file
+    m_fileNewed = (filep == NULL);
+    m_filep = m_fileNewed ? new VerilatedVcdFile : filep;
+    m_namemapp = NULL;
+    m_timeRes = m_timeUnit = 1e-9;
+    m_timeLastDump = 0;
+    m_sigs_oldvalp = NULL;
+    m_evcd = false;
+    m_scopeEscape = '.';  // Backward compatibility
+    m_fullDump = true;
+    m_wrChunkSize = 8*1024;
+    m_wrBufp = new char [m_wrChunkSize*8];
+    m_wrFlushp = m_wrBufp + m_wrChunkSize * 6;
+    m_writep = m_wrBufp;
+    m_wroteBytes = 0;
+}
+
 void VerilatedVcd::open (const char* filename) {
     if (isOpen()) return;
 
@@ -142,9 +179,7 @@ void VerilatedVcd::openNext (bool incFilename) {
 	assert(0);	// Not supported yet.
     } else {
 	// cppcheck-suppress duplicateExpression
-	m_fd = ::open (m_filename.c_str(), O_CREAT|O_WRONLY|O_TRUNC|O_LARGEFILE|O_NONBLOCK
-		       , 0666);
-	if (m_fd<0) {
+	if (!m_filep->open(m_filename)) {
 	    // User code can check isOpen()
 	    m_isOpen = false;
 	    return;
@@ -199,6 +234,7 @@ VerilatedVcd::~VerilatedVcd() {
     if (m_wrBufp) { delete[] m_wrBufp; m_wrBufp=NULL; }
     if (m_sigs_oldvalp) { delete[] m_sigs_oldvalp; m_sigs_oldvalp=NULL; }
     deleteNameMap();
+    if (m_filep && m_fileNewed) { delete m_filep; m_filep = NULL; }
     // Remove from list of traces
     vector<VerilatedVcd*>::iterator pos = find(s_vcdVecp.begin(), s_vcdVecp.end(), this);
     if (pos != s_vcdVecp.end()) { s_vcdVecp.erase(pos); }
@@ -209,7 +245,7 @@ void VerilatedVcd::closePrev () {
 
     bufferFlush();
     m_isOpen = false;
-    ::close(m_fd);
+    m_filep->close();
 }
 
 void VerilatedVcd::closeErr () {
@@ -219,7 +255,7 @@ void VerilatedVcd::closeErr () {
 
     // No buffer flush, just fclose
     m_isOpen = false;
-    ::close(m_fd);  // May get error, just ignore it
+    m_filep->close();  // May get error, just ignore it
 }
 
 void VerilatedVcd::close() {
@@ -285,7 +321,7 @@ void VerilatedVcd::bufferFlush () {
 	ssize_t remaining = (m_writep - wp);
 	if (remaining==0) break;
 	errno = 0;
-	ssize_t got = write (m_fd, wp, remaining);
+	ssize_t got = m_filep->write(wp, remaining);
 	if (got>0) {
 	    wp += got;
 	    m_wroteBytes += got;
diff --git a/include/verilated_vcd_c.h b/include/verilated_vcd_c.h
index a2d9ca8d7..76f7be70b 100644
--- a/include/verilated_vcd_c.h
+++ b/include/verilated_vcd_c.h
@@ -36,6 +36,22 @@ class VerilatedVcd;
 class VerilatedVcdCallInfo;
 
 // SPDIFF_ON
+//=============================================================================
+// VerilatedFile
+/// File handling routines, which can be overrode for e.g. socket I/O
+
+class VerilatedVcdFile {
+private:
+    int			m_fd;		///< File descriptor we're writing to
+public:
+    // METHODS
+    VerilatedVcdFile() : m_fd(0) {}
+    virtual ~VerilatedVcdFile() {}
+    virtual bool open(const string& name);
+    virtual void close();
+    virtual ssize_t write(const char* bufp, ssize_t len);
+};
+
 //=============================================================================
 // VerilatedVcdSig
 /// Internal data on one signal being traced.
@@ -62,9 +78,10 @@ typedef void (*VerilatedVcdCallback_t)(VerilatedVcd* vcdp, void* userthis, vluin
 
 class VerilatedVcd {
 private:
+    VerilatedVcdFile*	m_filep;	///< File we're writing to
+    bool		m_fileNewed;	///< m_filep needs destruction
     bool 		m_isOpen;	///< True indicates open file
     bool		m_evcd;		///< True for evcd format
-    int			m_fd;		///< File descriptor we're writing to
     string		m_filename;	///< Filename we're writing to (if open)
     vluint64_t		m_rolloverMB;	///< MB of file size to rollover at
     char		m_scopeEscape;	///< Character to separate scope components
@@ -135,21 +152,7 @@ protected:
 
 public:
     // CREATORS
-    VerilatedVcd () : m_isOpen(false), m_rolloverMB(0), m_modDepth(0), m_nextCode(1) {
-	m_namemapp = NULL;
-	m_timeRes = m_timeUnit = 1e-9;
-	m_timeLastDump = 0;
-	m_sigs_oldvalp = NULL;
-	m_evcd = false;
-	m_scopeEscape = '.';  // Backward compatibility
-	m_fd = 0;
-	m_fullDump = true;
-	m_wrChunkSize = 8*1024;
-	m_wrBufp = new char [m_wrChunkSize*8];
-	m_wrFlushp = m_wrBufp + m_wrChunkSize * 6;
-	m_writep = m_wrBufp;
-	m_wroteBytes = 0;
-    }
+    VerilatedVcd(VerilatedVcdFile* filep=NULL);
     ~VerilatedVcd();
 
     // ACCESSORS
diff --git a/test_regress/t/t_vpi_get.cpp b/test_regress/t/t_vpi_get.cpp
index c6bc3ac93..a6f6cee74 100644
--- a/test_regress/t/t_vpi_get.cpp
+++ b/test_regress/t/t_vpi_get.cpp
@@ -245,10 +245,10 @@ int main(int argc, char **argv, char **env) {
 # endif
 #endif
 
-    Verilated::traceEverOn(true);
-    VerilatedVcdC* tfp = new VerilatedVcdC;
 #if VM_TRACE
+    Verilated::traceEverOn(true);
     VL_PRINTF("Enabling waves...\n");
+    VerilatedVcdC* tfp = new VerilatedVcdC;
     topp->trace (tfp, 99);
     tfp->open ("obj_dir/t_vpi_var/simx.vcd");
 #endif
diff --git a/test_regress/t/t_vpi_memory.cpp b/test_regress/t/t_vpi_memory.cpp
index 57c7bd41f..e5234d69f 100644
--- a/test_regress/t/t_vpi_memory.cpp
+++ b/test_regress/t/t_vpi_memory.cpp
@@ -228,10 +228,10 @@ int main(int argc, char **argv, char **env) {
 # endif
 #endif
 
-    Verilated::traceEverOn(true);
-    VerilatedVcdC* tfp = new VerilatedVcdC;
 #if VM_TRACE
+    Verilated::traceEverOn(true);
     VL_PRINTF("Enabling waves...\n");
+    VerilatedVcdC* tfp = new VerilatedVcdC;
     topp->trace (tfp, 99);
     tfp->open ("obj_dir/t_vpi_var/simx.vcd");
 #endif
diff --git a/test_regress/t/t_vpi_unimpl.cpp b/test_regress/t/t_vpi_unimpl.cpp
index 4fb396590..4fa1a6546 100644
--- a/test_regress/t/t_vpi_unimpl.cpp
+++ b/test_regress/t/t_vpi_unimpl.cpp
@@ -159,10 +159,10 @@ int main(int argc, char **argv, char **env) {
 # endif
 #endif
 
-    Verilated::traceEverOn(true);
-    VerilatedVcdC* tfp = new VerilatedVcdC;
 #if VM_TRACE
+    Verilated::traceEverOn(true);
     VL_PRINTF("Enabling waves...\n");
+    VerilatedVcdC* tfp = new VerilatedVcdC;
     topp->trace (tfp, 99);
     tfp->open ("obj_dir/t_vpi_var/simx.vcd");
 #endif
diff --git a/test_regress/t/t_vpi_var.cpp b/test_regress/t/t_vpi_var.cpp
index ce8996615..5c21fa592 100644
--- a/test_regress/t/t_vpi_var.cpp
+++ b/test_regress/t/t_vpi_var.cpp
@@ -660,10 +660,10 @@ int main(int argc, char **argv, char **env) {
 # endif
 #endif
 
-    Verilated::traceEverOn(true);
-    VerilatedVcdC* tfp = new VerilatedVcdC;
 #if VM_TRACE
+    Verilated::traceEverOn(true);
     VL_PRINTF("Enabling waves...\n");
+    VerilatedVcdC* tfp = new VerilatedVcdC;
     topp->trace (tfp, 99);
     tfp->open ("obj_dir/t_vpi_var/simx.vcd");
 #endif