diff --git a/Makefile.in b/Makefile.in
index 846462440..854054f32 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -68,7 +68,7 @@ dllib=@DLLIB@
 
 # For a cross compile these defines will need to be set accordingly.
 HOSTCC = @CC@
-HOSTCFLAGS = @WARNING_FLAGS@ @CFLAGS@
+HOSTCFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 
 CC = @CC@
 CXX = @CXX@
@@ -90,7 +90,7 @@ INCLUDE_PATH = -I. -I$(srcdir) -I$(srcdir)/libmisc
 endif
 
 CPPFLAGS = @DEFS@ $(INCLUDE_PATH) @CPPFLAGS@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 CXXFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CXX@ @CXXFLAGS@
 PICFLAGS = @PICFLAG@
 LDFLAGS = @rdynamic@ @LDFLAGS@
diff --git a/cadpli/Makefile.in b/cadpli/Makefile.in
index e3a0eb559..ba347b72c 100644
--- a/cadpli/Makefile.in
+++ b/cadpli/Makefile.in
@@ -43,7 +43,7 @@ INCLUDE_PATH = -I. -I.. -I$(srcdir) -I$(srcdir)/..
 endif
 
 CPPFLAGS = $(INCLUDE_PATH) @CPPFLAGS@ @DEFS@ @PICFLAG@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 LDFLAGS = @LDFLAGS@
 
 O = cadpli.o
diff --git a/configure.in b/configure.in
index 2cef580fd..de2a76f75 100644
--- a/configure.in
+++ b/configure.in
@@ -81,8 +81,9 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[]])],
 CFLAGS="$iverilog_temp_cflags"
 
 AC_SUBST(DEPENDENCY_FLAG, [-MD])
-AC_SUBST(WARNING_FLAGS, ["-Wall -Wshadow"])
-AC_SUBST(WARNING_FLAGS_CXX, ["$iverilog_wextra_flag"])
+AC_SUBST(WARNING_FLAGS, ["-Wall $iverilog_wextra_flag -Wshadow"])
+AC_SUBST(WARNING_FLAGS_CC, ["-Wno-unused -Wno-sign-compare -Wno-type-limits"])
+AC_SUBST(WARNING_FLAGS_CXX, [""])
 fi
 
 AC_LANG(C++)
diff --git a/driver-vpi/Makefile.in b/driver-vpi/Makefile.in
index 731e155eb..d462cc2f2 100644
--- a/driver-vpi/Makefile.in
+++ b/driver-vpi/Makefile.in
@@ -48,7 +48,7 @@ INCLUDE_PATH = -I. -I.. -I$(srcdir) -I$(srcdir)/..
 endif
 
 CPPFLAGS = $(INCLUDE_PATH) @CPPFLAGS@ @DEFS@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 LDFLAGS = @LDFLAGS@
 
 O = main.o res.o
diff --git a/driver/Makefile.in b/driver/Makefile.in
index a5b5c4cdf..b2ad7150c 100644
--- a/driver/Makefile.in
+++ b/driver/Makefile.in
@@ -49,7 +49,7 @@ INCLUDE_PATH = -I. -I.. -I$(srcdir) -I$(srcdir)/..
 endif
 
 CPPFLAGS = $(INCLUDE_PATH) @CPPFLAGS@ @DEFS@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 LDFLAGS = @LDFLAGS@
 
 O = main.o substit.o cflexor.o cfparse.o
diff --git a/ivlpp/Makefile.in b/ivlpp/Makefile.in
index ffcafe6a9..07053c298 100644
--- a/ivlpp/Makefile.in
+++ b/ivlpp/Makefile.in
@@ -44,7 +44,7 @@ INCLUDE_PATH = -I. -I.. -I$(srcdir) -I$(srcdir)/..
 endif
 
 CPPFLAGS = $(INCLUDE_PATH) @CPPFLAGS@ @DEFS@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 LDFLAGS = @LDFLAGS@
 
 O = main.o lexor.o
diff --git a/libveriuser/Makefile.in b/libveriuser/Makefile.in
index e6d843927..868f3e257 100644
--- a/libveriuser/Makefile.in
+++ b/libveriuser/Makefile.in
@@ -48,7 +48,7 @@ LDRELOCFLAGS = @LDRELOCFLAGS@
 LDTARGETFLAGS = @LDTARGETFLAGS@
 
 CPPFLAGS = $(INCLUDE_PATH) @CPPFLAGS@ @DEFS@ @PICFLAG@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 
 A = a_close.o a_compare_handles.o a_configure.o a_fetch_argc.o \
     a_fetch_argv.o a_fetch_dir.o a_fetch_fullname.o a_fetch_location.o \
diff --git a/libveriuser/veriusertfs.c b/libveriuser/veriusertfs.c
index cf7b156a7..4f804ccf0 100644
--- a/libveriuser/veriusertfs.c
+++ b/libveriuser/veriusertfs.c
@@ -370,7 +370,7 @@ PLI_INT32 tf_irosynchronize(void*obj)
       vpiHandle sys = (vpiHandle)obj;
       p_pli_data pli = vpi_get_userdata(sys);
       s_cb_data cb;
-      s_vpi_time ti = {vpiSuppressTime, 0, 0};
+      s_vpi_time ti = {vpiSuppressTime, 0, 0, 0.0};
 
       cb.reason = cbReadOnlySynch;
       cb.cb_rtn = callback;
@@ -397,7 +397,7 @@ PLI_INT32 tf_isetrealdelay(double dly, void*obj)
       vpiHandle sys = (vpiHandle)obj;
       p_pli_data pli = vpi_get_userdata(sys);
       s_cb_data cb;
-      s_vpi_time ti = {vpiSimTime};
+      s_vpi_time ti = {vpiSimTime, 0, 0, 0.0};
 
       /* Scale delay to SimTime */
       ivl_u64_t delay = ((dly
diff --git a/tgt-fpga/Makefile.in b/tgt-fpga/Makefile.in
index 1bb9e697f..72546b5a6 100644
--- a/tgt-fpga/Makefile.in
+++ b/tgt-fpga/Makefile.in
@@ -44,7 +44,7 @@ INCLUDE_PATH = -I. -I.. -I$(srcdir) -I$(srcdir)/..
 endif
 
 CPPFLAGS = $(INCLUDE_PATH) @CPPFLAGS@ @DEFS@ @PICFLAG@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 LDFLAGS = @LDFLAGS@
 
 D = d-generic.o d-generic-edif.o d-lpm.o d-virtex.o d-virtex2.o
diff --git a/tgt-null/Makefile.in b/tgt-null/Makefile.in
index 997905fe9..c414f2fbe 100644
--- a/tgt-null/Makefile.in
+++ b/tgt-null/Makefile.in
@@ -40,7 +40,7 @@ INCLUDE_PATH = -I. -I.. -I$(srcdir) -I$(srcdir)/..
 endif
 
 CPPFLAGS = $(INCLUDE_PATH) @CPPFLAGS@ @DEFS@ @PICFLAG@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 LDFLAGS = @LDFLAGS@
 
 O = null.o
diff --git a/tgt-pal/Makefile.in b/tgt-pal/Makefile.in
index 0efa180d4..291acac9d 100644
--- a/tgt-pal/Makefile.in
+++ b/tgt-pal/Makefile.in
@@ -39,7 +39,7 @@ INCLUDE_PATH = -I. -I.. -I$(srcdir) -I$(srcdir)/..
 endif
 
 CPPFLAGS = $(INCLUDE_PATH) @CPPFLAGS@ @DEFS@ @PICFLAG@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 LDFLAGS = @LDFLAGS@
 
 O = imain.o dump_final.o emit_jed.o enables.o fit_log.o fit_reg.o pads.o
diff --git a/tgt-stub/Makefile.in b/tgt-stub/Makefile.in
index 874cbc3bf..c136ca37c 100644
--- a/tgt-stub/Makefile.in
+++ b/tgt-stub/Makefile.in
@@ -41,7 +41,7 @@ INCLUDE_PATH = -I. -I.. -I$(srcdir) -I$(srcdir)/..
 endif
 
 CPPFLAGS = $(INCLUDE_PATH) @CPPFLAGS@ @DEFS@ @PICFLAG@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 LDFLAGS = @LDFLAGS@
 
 O = stub.o classes.o constant.o enumerate.o expression.o statement.o switches.o types.o
diff --git a/tgt-verilog/Makefile.in b/tgt-verilog/Makefile.in
index 2c7ebc3e1..40d6c27d9 100644
--- a/tgt-verilog/Makefile.in
+++ b/tgt-verilog/Makefile.in
@@ -39,7 +39,7 @@ INCLUDE_PATH = -I. -I.. -I$(srcdir) -I$(srcdir)/..
 endif
 
 CPPFLAGS = @ident_support@ $(INCLUDE_PATH) @CPPFLAGS@ @DEFS@ @PICFLAG@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 LDFLAGS = @LDFLAGS@
 
 O = verilog.o
diff --git a/tgt-vlog95/Makefile.in b/tgt-vlog95/Makefile.in
index 69a57b618..bd0a9ba1c 100644
--- a/tgt-vlog95/Makefile.in
+++ b/tgt-vlog95/Makefile.in
@@ -40,7 +40,7 @@ INCLUDE_PATH = -I. -I.. -I$(srcdir) -I$(srcdir)/..
 endif
 
 CPPFLAGS = $(INCLUDE_PATH) @CPPFLAGS@ @DEFS@ @PICFLAG@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 LDFLAGS = @LDFLAGS@
 
 O = vlog95.o event.o expr.o logic_lpm.o misc.o numbers.o scope.o stmt.o udp.o
diff --git a/tgt-vvp/Makefile.in b/tgt-vvp/Makefile.in
index 37083138e..781374442 100644
--- a/tgt-vvp/Makefile.in
+++ b/tgt-vvp/Makefile.in
@@ -44,7 +44,7 @@ INCLUDE_PATH = -I. -I.. -I$(srcdir) -I$(srcdir)/..
 endif
 
 CPPFLAGS = $(INCLUDE_PATH) @CPPFLAGS@ @DEFS@ @PICFLAG@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 LDFLAGS = @LDFLAGS@
 
 O = vvp.o draw_class.o draw_enum.o draw_mux.o draw_net_input.o \
diff --git a/vhdlpp/Makefile.in b/vhdlpp/Makefile.in
index 15c9523ab..e3622a7c3 100644
--- a/vhdlpp/Makefile.in
+++ b/vhdlpp/Makefile.in
@@ -51,7 +51,6 @@ INCLUDE_PATH = -I. -I.. -I$(srcdir) -I$(srcdir)/.. -I$(srcdir)/../libmisc
 endif
 
 CPPFLAGS = $(INCLUDE_PATH) @CPPFLAGS@ @DEFS@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
 CXXFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CXX@ @CXXFLAGS@
 LDFLAGS = @LDFLAGS@
 LIBS = @LIBS@ @EXTRALIBS@
diff --git a/vpi/Makefile.in b/vpi/Makefile.in
index 82b0a9094..50e367d6a 100644
--- a/vpi/Makefile.in
+++ b/vpi/Makefile.in
@@ -46,7 +46,7 @@ INCLUDE_PATH = -I. -I.. -I$(srcdir) -I$(srcdir)/..
 endif
 
 CPPFLAGS = $(INCLUDE_PATH) @file64_support@ @CPPFLAGS@ @DEFS@ @PICFLAG@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 CXXFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CXX@ @CXXFLAGS@
 LDFLAGS = @LDFLAGS@
 
diff --git a/vvp/Makefile.in b/vvp/Makefile.in
index d7e8ce35e..61d9fc5c0 100644
--- a/vvp/Makefile.in
+++ b/vvp/Makefile.in
@@ -33,7 +33,7 @@ includedir = @includedir@
 
 # For a cross compile these defines will need to be set accordingly.
 HOSTCC = @CC@
-HOSTCFLAGS = @WARNING_FLAGS@ @CFLAGS@
+HOSTCFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 
 CC = @CC@
 CXX = @CXX@
@@ -56,7 +56,7 @@ INCLUDE_PATH = -I. -I.. -I$(srcdir) -I$(srcdir)/..
 endif
 
 CPPFLAGS = $(INCLUDE_PATH) @CPPFLAGS@ @DEFS@
-CFLAGS = @WARNING_FLAGS@ @CFLAGS@
+CFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 CXXFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CXX@ @CXXFLAGS@
 LDFLAGS = @rdynamic@ @LDFLAGS@
 LIBS = @LIBS@ @EXTRALIBS@