diff --git a/config.h.in b/config.h.in
index 30470a22b..8bac481be 100644
--- a/config.h.in
+++ b/config.h.in
@@ -27,6 +27,10 @@
 #  endif
 #endif
 
+# define SIZEOF_UNSIGNED_LONG_LONG 0
+
+# define SIZEOF_SIZE_T 0
+
 # undef NEED_LU
 # undef NEED_TU
 # undef WLU
@@ -62,4 +66,14 @@
  */
 # undef CHECK_WITH_VALGRIND
 
+#ifdef __MINGW32__
+# if SIZEOF_SIZE_T == SIZEOF_UNSIGNED_LONG_LONG
+#  define SIZE_FMT_D "llu"
+# else
+#  define SIZE_FMT_D "u"
+# endif
+#else
+# define SIZE_FMT_D "zu"
+#endif
+
 #endif /* IVL_config_H */
diff --git a/configure.in b/configure.in
index 7fa9bc8e4..8d9be4ad9 100644
--- a/configure.in
+++ b/configure.in
@@ -131,6 +131,7 @@ CXXFLAGS="$iverilog_temp_cxxflags"
 AC_CHECK_SIZEOF(unsigned long long)
 AC_CHECK_SIZEOF(unsigned long)
 AC_CHECK_SIZEOF(unsigned)
+AC_CHECK_SIZEOF(size_t)
 
 # vvp uses these...
 AC_CHECK_LIB(termcap, tputs)
diff --git a/ivlpp/lexor.lex b/ivlpp/lexor.lex
index f7d76422d..38b78c995 100644
--- a/ivlpp/lexor.lex
+++ b/ivlpp/lexor.lex
@@ -1898,11 +1898,7 @@ static int load_next_input(void)
 static void do_dump_precompiled_defines(FILE* out, struct define_t* table)
 {
     if (!table->keyword)
-#ifdef __MINGW32__  /* MinGW does not know about z. */
-        fprintf(out, "%s:%d:%d:%s\n", table->name, table->argc, strlen(table->value), table->value);
-#else
-        fprintf(out, "%s:%d:%zd:%s\n", table->name, table->argc, strlen(table->value), table->value);
-#endif
+        fprintf(out, "%s:%d:%" SIZE_FMT_D ":%s\n", table->name, table->argc, strlen(table->value), table->value);
 
     if (table->left) do_dump_precompiled_defines(out, table->left);
 
diff --git a/vvp/config.h.in b/vvp/config.h.in
index 24b0aa802..1a7151ac3 100644
--- a/vvp/config.h.in
+++ b/vvp/config.h.in
@@ -33,6 +33,8 @@
 #endif
 # define SIZEOF_UNSIGNED 0
 
+# define SIZEOF_SIZE_T 0
+
 # undef NEED_LU
 # undef NEED_TU
 # undef WLU
@@ -133,6 +135,16 @@ typedef unsigned long vvp_time64_t;
 
 #endif /* HAVE_INTTYPES_H */
 
+#ifdef __MINGW32__
+# if SIZEOF_SIZE_T == SIZEOF_UNSIGNED_LONG_LONG
+#  define SIZE_FMT_U "llu"
+# else
+#  define SIZE_FMT_U "u"
+# endif
+#else
+# define SIZE_FMT_U "zu"
+#endif
+
 # include  <cmath>
 
 /* getrusage, /proc/self/statm */
diff --git a/vvp/main.cc b/vvp/main.cc
index ae2457155..801ee4e35 100644
--- a/vvp/main.cc
+++ b/vvp/main.cc
@@ -464,34 +464,18 @@ int main(int argc, char*argv[])
       }
 
       if (verbose_flag) {
-#ifdef __MINGW32__  /* MinGW does not know about z. */
-	    vpi_mcd_printf(1, " ... %8lu functors (net_fun pool=%u bytes)\n",
-#else
-	    vpi_mcd_printf(1, " ... %8lu functors (net_fun pool=%zu bytes)\n",
-#endif
+	    vpi_mcd_printf(1, " ... %8lu functors (net_fun pool=%" SIZE_FMT_U " bytes)\n",
 			   count_functors, vvp_net_fun_t::heap_total());
 	    vpi_mcd_printf(1, "           %8lu logic\n",  count_functors_logic);
 	    vpi_mcd_printf(1, "           %8lu bufif\n",  count_functors_bufif);
 	    vpi_mcd_printf(1, "           %8lu resolv\n",count_functors_resolv);
 	    vpi_mcd_printf(1, "           %8lu signals\n", count_functors_sig);
-#ifdef __MINGW32__  /* MinGW does not know about z. */
-	    vpi_mcd_printf(1, " ... %8lu filters (net_fil pool=%u bytes)\n",
-#else
-	    vpi_mcd_printf(1, " ... %8lu filters (net_fil pool=%zu bytes)\n",
-#endif
+	    vpi_mcd_printf(1, " ... %8lu filters (net_fil pool=%" SIZE_FMT_U " bytes)\n",
 			   count_filters, vvp_net_fil_t::heap_total());
-#ifdef __MINGW32__  /* MinGW does not know about z. */
-	    vpi_mcd_printf(1, " ... %8lu opcodes (%u bytes)\n",
-#else
-	    vpi_mcd_printf(1, " ... %8lu opcodes (%zu bytes)\n",
-#endif
+	    vpi_mcd_printf(1, " ... %8lu opcodes (%" SIZE_FMT_U " bytes)\n",
 	                   count_opcodes, size_opcodes);
 	    vpi_mcd_printf(1, " ... %8lu nets\n",     count_vpi_nets);
-#ifdef __MINGW32__  /* MinGW does not know about z. */
-	    vpi_mcd_printf(1, " ... %8lu vvp_nets (%u bytes)\n",
-#else
-	    vpi_mcd_printf(1, " ... %8lu vvp_nets (%zu bytes)\n",
-#endif
+	    vpi_mcd_printf(1, " ... %8lu vvp_nets (%" SIZE_FMT_U " bytes)\n",
 			   count_vvp_nets, size_vvp_nets);
 	    vpi_mcd_printf(1, " ... %8lu arrays (%lu words)\n",
 			   count_net_arrays, count_net_array_words);
diff --git a/vvp/udp.cc b/vvp/udp.cc
index 407952c6b..8ea8b8e06 100644
--- a/vvp/udp.cc
+++ b/vvp/udp.cc
@@ -266,11 +266,7 @@ void vvp_udp_comb_s::compile_table(char**tab)
 	    cur.maskx = 0;
 	    if (port_count() > 8*sizeof(cur.mask0)) {
 		  fprintf(stderr, "internal error: primitive port count=%u "
-#ifdef __MINGW32__  /* MinGW does not know about z. */
-			  " > %u\n", port_count(), sizeof(cur.mask0));
-#else
-			  " > %zu\n", port_count(), sizeof(cur.mask0));
-#endif
+			  " > %" SIZE_FMT_U "\n", port_count(), sizeof(cur.mask0));
 		  assert(port_count() <= 8*sizeof(cur.mask0));
 	    }
 	    for (unsigned pp = 0 ;  pp < port_count() ;  pp += 1) {