diff --git a/Changes b/Changes
index d75f574f7..1b276018a 100644
--- a/Changes
+++ b/Changes
@@ -13,6 +13,8 @@ indicates the contributor was also the author of the fix; Thanks!
 
 ***  Support $fopen and I/O with integer instead of `verilator_file_descriptor.
 
+**** Fix vpi_register_cb using bad s_cb_data, bug370.  [by Thomas Watts]
+
 **** Fix $display missing leading zeros in %0d, bug367.  [Alex Solomatnikov]
 
 **** Use 'vluint64_t' for SystemC instead of (same sized) 'uint64' for MSVC++.
diff --git a/include/verilated.cpp b/include/verilated.cpp
index fa873ee4e..bf911fa4d 100644
--- a/include/verilated.cpp
+++ b/include/verilated.cpp
@@ -714,17 +714,21 @@ IData VL_FGETS_IXI(int obits, void* destp, IData fpi) {
     return got;
 }
 
-QData VL_FOPEN_QI(QData filename, IData mode) {
+IData VL_FOPEN_QI(QData filename, IData mode) {
     IData fnw[2];  VL_SET_WQ(fnw, filename);
     return VL_FOPEN_WI(2, fnw, mode);
 }
-QData VL_FOPEN_WI(int fnwords, WDataInP filenamep, IData mode) {
+IData VL_FOPEN_WI(int fnwords, WDataInP filenamep, IData mode) {
     char filenamez[VL_TO_STRING_MAX_WORDS*VL_WORDSIZE+1];
     _VL_VINT_TO_STRING(fnwords*VL_WORDSIZE, filenamez, filenamep);
     char modez[5];
     _VL_VINT_TO_STRING(VL_WORDSIZE, modez, &mode);
-    return VerilatedImp::fdNew(fopen(filenamez,modez));
+    return VL_FOPEN_S(filenamez,modez);
 }
+IData VL_FOPEN_S(const char* filenamep, const char* modep) {
+    return VerilatedImp::fdNew(fopen(filenamep,modep));
+}
+
 void VL_FCLOSE_I(IData fdi) {
     FILE* fp = VL_CVT_I_FP(fdi);
     if (VL_UNLIKELY(!fp)) return;
diff --git a/include/verilated.h b/include/verilated.h
index fb60fbc4f..49471c18f 100644
--- a/include/verilated.h
+++ b/include/verilated.h
@@ -324,9 +324,10 @@ extern WDataOutP _vl_moddiv_w(int lbits, WDataOutP owp, WDataInP lwp, WDataInP r
 /// File I/O
 extern IData VL_FGETS_IXI(int obits, void* destp, IData fpi);
 
-extern QData VL_FOPEN_WI(int fnwords, WDataInP ofilename, IData mode);
-extern QData VL_FOPEN_QI(QData ofilename, IData mode);
-inline QData VL_FOPEN_II(IData ofilename, IData mode) { return VL_FOPEN_QI(ofilename,mode); }
+extern IData VL_FOPEN_S(const char* filenamep, const char* mode);
+extern IData VL_FOPEN_WI(int fnwords, WDataInP ofilename, IData mode);
+extern IData VL_FOPEN_QI(QData ofilename, IData mode);
+inline IData VL_FOPEN_II(IData ofilename, IData mode) { return VL_FOPEN_QI(ofilename,mode); }
 
 extern void VL_FCLOSE_I(IData fdi);
 
diff --git a/include/verilated_vpi.h b/include/verilated_vpi.h
index 2668997a7..211295851 100644
--- a/include/verilated_vpi.h
+++ b/include/verilated_vpi.h
@@ -95,9 +95,12 @@ typedef PLI_INT32 (*VerilatedPliCb)(struct t_cb_data *);
 
 class VerilatedVpioCb : public VerilatedVpio {
     t_cb_data		m_cbData;
+    s_vpi_value		m_value;
     QData		m_time;
 public:
-    VerilatedVpioCb(const t_cb_data* cbDatap, QData time) : m_cbData(*cbDatap), m_time(time) {}
+    VerilatedVpioCb(const t_cb_data* cbDatap, QData time) : m_cbData(*cbDatap), m_time(time) {
+	m_cbData.value = &m_value;
+    }
     virtual ~VerilatedVpioCb() {}
     static inline VerilatedVpioCb* castp(vpiHandle h) { return dynamic_cast<VerilatedVpioCb*>((VerilatedVpio*)h); }
     vluint32_t reason() const { return m_cbData.reason; }
@@ -326,6 +329,7 @@ public:
 		    VL_DEBUG_IF_PLI(VL_PRINTF("-vltVpi:  value_callback %p %s v[0]=%d\n",
 					      vop,varop->fullname(), *((CData*)newDatap)););
 		    memcpy(prevDatap, newDatap, varop->entSize());
+		    vpi_get_value(vop->cb_datap()->obj, vop->cb_datap()->value);
 		    (vop->cb_rtnp()) (vop->cb_datap());
 		}
 	    }
@@ -735,19 +739,26 @@ vpiHandle vpi_put_value(vpiHandle object, p_vpi_value value_p,
 
 // I/O routines
 
-//-PLI_UINT32 vpi_mcd_open(PLI_BYTE8 *fileName) {
-//-    _VL_VPI_UNIMP(); return 0;
-//-}
-//-PLI_UINT32 vpi_mcd_close(PLI_UINT32 mcd) {
-//-    _VL_VPI_UNIMP(); return 0;
-//-}
-//-PLI_BYTE8 *vpi_mcd_name(PLI_UINT32 cd) {
-//-    _VL_VPI_UNIMP(); return 0;
-//-}
-//-PLI_INT32 vpi_mcd_printf(PLI_UINT32 mcd, PLI_BYTE8 *format, ...) {
+PLI_UINT32 vpi_mcd_open(PLI_BYTE8 *filenamep) {
+    return VL_FOPEN_S(filenamep,"wb");
+}
+
+PLI_UINT32 vpi_mcd_close(PLI_UINT32 mcd) {
+    VL_FCLOSE_I(mcd); return 0;
+}
+
+//-PLI_BYTE8 *vpi_mcd_name(PLI_UINT32 mcd) {
 //-    _VL_VPI_UNIMP(); return 0;
 //-}
 
+PLI_INT32 vpi_mcd_printf(PLI_UINT32 mcd, PLI_BYTE8 *formatp, ...) {
+    va_list ap;
+    va_start(ap,formatp);
+    int chars = vpi_mcd_vprintf(mcd, formatp, ap);
+    va_end(ap);
+    return chars;
+}
+
 PLI_INT32 vpi_printf(PLI_BYTE8 *formatp, ...) {
     va_list ap;
     va_start(ap,formatp);
@@ -760,15 +771,24 @@ PLI_INT32 vpi_vprintf(PLI_BYTE8* formatp, va_list ap) {
     return VL_VPRINTF(formatp, ap);
 }
 
-//-PLI_INT32 vpi_mcd_vprintf(PLI_UINT32 mcd, PLI_BYTE8 *format, va_list ap) {
-//-    _VL_VPI_UNIMP(); return 0;
-//-}
-//-PLI_INT32 vpi_flush(void) {
-//-    _VL_VPI_UNIMP(); return 0;
-//-}
-//-PLI_INT32 vpi_mcd_flush(PLI_UINT32 mcd) {
-//-    _VL_VPI_UNIMP(); return 0;
-//-}
+PLI_INT32 vpi_mcd_vprintf(PLI_UINT32 mcd, PLI_BYTE8 *format, va_list ap) {
+    FILE* fp = VL_CVT_I_FP(mcd);
+    if (VL_UNLIKELY(!fp)) return 0;
+    int chars = vfprintf(fp, format, ap);
+    return chars;
+}
+
+PLI_INT32 vpi_flush(void) {
+    Verilated::flushCall();
+    return 0;
+}
+
+PLI_INT32 vpi_mcd_flush(PLI_UINT32 mcd) {
+    FILE* fp = VL_CVT_I_FP(mcd);
+    if (VL_UNLIKELY(!fp)) return 1;
+    fflush(fp);
+    return 0;
+}
 
 // utility routines
 
diff --git a/test_regress/t/t_vpi_var.cpp b/test_regress/t/t_vpi_var.cpp
index 9cab34c66..ef540b072 100644
--- a/test_regress/t/t_vpi_var.cpp
+++ b/test_regress/t/t_vpi_var.cpp
@@ -28,6 +28,10 @@
 // __FILE__ is too long
 #define FILENM "t_vpi_var.cpp"
 
+unsigned int main_time = false;
+unsigned int callback_count = false;
+unsigned int callback_count_half = false;
+
 //======================================================================
 
 
@@ -72,6 +76,35 @@ public:
 	return __LINE__; \
     }
 
+int _mon_check_mcd() {
+    PLI_INT32 status;
+    
+    PLI_UINT32 mcd;
+    PLI_BYTE8* filename = (PLI_BYTE8*)"mcd_open.tmp";
+    mcd = vpi_mcd_open(filename);
+    CHECK_RESULT_NZ(mcd);
+
+    {   // Check it got written
+	FILE* fp = fopen(filename,"r");
+	CHECK_RESULT_NZ(fp);
+	fclose(fp);
+    }
+
+    status = vpi_mcd_printf(mcd, (PLI_BYTE8*)"hello %s", "vpi_mcd_printf");
+    CHECK_RESULT(status, strlen("hello vpi_mcd_printf"));
+
+    status = vpi_mcd_flush(mcd);
+    CHECK_RESULT(status, 0);
+
+    status = vpi_mcd_close(mcd);
+    CHECK_RESULT(status, 0);
+
+    status = vpi_flush();
+    CHECK_RESULT(status, 0);
+
+    return 0;
+}
+
 int _mon_check_callbacks() {
     t_cb_data cb_data;
     cb_data.reason = cbEndOfSimulation;
@@ -87,6 +120,46 @@ int _mon_check_callbacks() {
     return 0;
 }
 
+int _value_callback(p_cb_data cb_data) {
+  CHECK_RESULT(cb_data->value->value.integer+10, main_time);
+  callback_count++;
+  return 0;
+}
+
+int _value_callback_half(p_cb_data cb_data) {
+  CHECK_RESULT(cb_data->value->value.integer*2+10, main_time);
+  callback_count_half++;
+  return 0;
+}
+
+int _mon_check_value_callbacks() {
+    vpiHandle vh1 = vpi_handle_by_name((PLI_BYTE8*)"t.count", NULL);
+    CHECK_RESULT_NZ(vh1);
+
+    s_vpi_value v;
+    v.format = vpiIntVal;
+    vpi_get_value(vh1, &v);
+
+    t_cb_data cb_data;
+    cb_data.reason = cbValueChange;
+    cb_data.cb_rtn = _value_callback;
+    cb_data.obj = vh1;
+    cb_data.value = &v;
+
+    vpiHandle vh = vpi_register_cb(&cb_data);
+    CHECK_RESULT_NZ(vh);
+
+    vh1 = vpi_handle_by_name((PLI_BYTE8*)"t.half_count", NULL);
+    CHECK_RESULT_NZ(vh1);
+
+    cb_data.obj = vh1;
+    cb_data.cb_rtn = _value_callback_half;
+
+    vh = vpi_register_cb(&cb_data);
+    CHECK_RESULT_NZ(vh);
+    return 0;
+}
+
 int _mon_check_var() {
     VlVpiHandle vh1 = vpi_handle_by_name((PLI_BYTE8*)"t.onebit", NULL);
     CHECK_RESULT_NZ(vh1);
@@ -245,7 +318,9 @@ int _mon_check_quad() {
 
 int mon_check() {
     // Callback from initial block in monitor
+    if (int status = _mon_check_mcd()) return status;
     if (int status = _mon_check_callbacks()) return status;
+    if (int status = _mon_check_value_callbacks()) return status;
     if (int status = _mon_check_var()) return status;
     if (int status = _mon_check_varlist()) return status;
     if (int status = _mon_check_getput()) return status;
@@ -255,7 +330,6 @@ int mon_check() {
 
 //======================================================================
 
-unsigned int main_time = false;
 
 double sc_time_stamp () {
     return main_time;
@@ -288,12 +362,15 @@ int main(int argc, char **argv, char **env) {
     while (sc_time_stamp() < sim_time && !Verilated::gotFinish()) {
 	main_time += 1;
 	topp->eval();
+	VerilatedVpi::callValueCbs();
 	topp->clk = !topp->clk;
 	//mon_do();
 #if VM_TRACE
 	if (tfp) tfp->dump (main_time);
 #endif
     }
+    CHECK_RESULT(callback_count, 501);
+    CHECK_RESULT(callback_count_half, 250);
     if (!Verilated::gotFinish()) {
 	vl_fatal(FILENM,__LINE__,"main", "%Error: Timeout; never got a $finish");
     }
diff --git a/test_regress/t/t_vpi_var.v b/test_regress/t/t_vpi_var.v
index 6600fab52..8d1aaf00b 100644
--- a/test_regress/t/t_vpi_var.v
+++ b/test_regress/t/t_vpi_var.v
@@ -19,6 +19,9 @@ module t (/*AUTOARG*/
 
    reg [3:2][61:0] quads	/*verilator public_flat_rw @(posedge clk) */;
 
+   reg [31:0] 	   count	/*verilator public_flat_rd */;
+   reg [31:0] 	   half_count	/*verilator public_flat_rd */;
+   
    integer 	  status;
 
    sub sub();
@@ -34,8 +37,17 @@ module t (/*AUTOARG*/
       if (onebit != 1'b1) $stop;
       if (quads[2] != 62'h12819213_abd31a1c) $stop;
       if (quads[3] != 62'h1c77bb9b_3784ea09) $stop;
-      $write("*-* All Finished *-*\n");
-      $finish;
+   end
+
+   always @(posedge clk) begin
+      count <= count + 2;
+      if (count[1])
+	half_count <= half_count + 2;
+
+      if (count == 1000) begin
+	 $write("*-* All Finished *-*\n");
+	 $finish;
+      end
    end
 
 endmodule