diff --git a/libsrc/stdio/vfprintf.c b/libsrc/stdio/vfprintf.c
index 9d361ae23..c429fe884 100644
--- a/libsrc/stdio/vfprintf.c
+++ b/libsrc/stdio/vfprintf.c
@@ -224,6 +224,7 @@ int vfprintf(FILE *fp, const char *fmt_, va_list ap) {
     int order = 0, suborder = 0;
     bool sign = false;
     bool leftalign = false;
+    bool sizez = false;
     int nlong = 0;
     c = fmt[++i];
 
@@ -265,16 +266,23 @@ int vfprintf(FILE *fp, const char *fmt_, va_list ap) {
         nlong = 2;
         c = fmt[++i];
       }
+    } else if (c == 'z') {
+      sizez = true;
+      c = fmt[++i];
     }
 
     switch (c) {
     case 'd':
       {
         long long x;
-        switch (nlong) {
-        case 0:  x = va_arg(ap, int); break;
-        case 1:  x = va_arg(ap, long); break;
-        default: x = va_arg(ap, long long); break;  // case 2:
+        if (sizez) {
+          x = va_arg(ap, ssize_t);
+        } else {
+          switch (nlong) {
+          case 0:  x = va_arg(ap, int); break;
+          case 1:  x = va_arg(ap, long); break;
+          default: x = va_arg(ap, long long); break;  // case 2:
+          }
         }
         bool negative = x < 0;
         unsigned long long ux = negative ? -x : x;
@@ -287,10 +295,14 @@ int vfprintf(FILE *fp, const char *fmt_, va_list ap) {
     case 'u':
       {
         unsigned long long x;
-        switch (nlong) {
-        case 0:  x = va_arg(ap, unsigned int); break;
-        case 1:  x = va_arg(ap, unsigned long); break;
-        default: x = va_arg(ap, unsigned long long); break;  // case 2:
+        if (sizez) {
+          x = va_arg(ap, size_t);
+        } else {
+          switch (nlong) {
+          case 0:  x = va_arg(ap, unsigned int); break;
+          case 1:  x = va_arg(ap, unsigned long); break;
+          default: x = va_arg(ap, unsigned long long); break;  // case 2:
+          }
         }
         char *p = snprintullong2(bufend, x, 10, kHexDigits);
         if (sign)
@@ -298,40 +310,18 @@ int vfprintf(FILE *fp, const char *fmt_, va_list ap) {
         o += snprintstr(fp, p, order, suborder, leftalign, padding);
       }
       break;
-    case 'z':
-      {
-        switch (fmt[i + 1]) {
-        case 'u':
-          {
-            ++i;
-            size_t x = va_arg(ap, size_t);
-            o += snprintullong(fp, x, 10, kHexDigits, order, padding);
-          }
-          break;
-        case 'd':
-          {
-            ++i;
-            ssize_t x = va_arg(ap, ssize_t);
-            bool negative = x < 0;
-            size_t ux = negative ? -x : x;
-            if (negative || order > 0 || sign)
-              o += sprintsign(fp, negative, sign, &order);
-            char *p = snprintullong2(bufend, ux, 10, kHexDigits);
-            o += snprintstr(fp, p, order, suborder, leftalign, padding);
-          }
-          break;
-        default: break;  // TODO: error
-        }
-      }
-      break;
     case 'x': case 'X':
       {
         const char *digits = c == 'x' ? kHexDigits : kUpperHexDigits;
         unsigned long long x;
-        switch (nlong) {
-        case 0:  x = va_arg(ap, unsigned int); break;
-        case 1:  x = va_arg(ap, unsigned long); break;
-        default: x = va_arg(ap, unsigned long long); break;  // case 2:
+        if (sizez) {
+          x = va_arg(ap, size_t);
+        } else {
+          switch (nlong) {
+          case 0:  x = va_arg(ap, unsigned int); break;
+          case 1:  x = va_arg(ap, unsigned long); break;
+          default: x = va_arg(ap, unsigned long long); break;  // case 2:
+          }
         }
         o += snprintullong(fp, x, 16, digits, order, padding);
       }
diff --git a/libsrc/tests/printf_test.c b/libsrc/tests/printf_test.c
index d376d0c75..fe8637cf7 100644
--- a/libsrc/tests/printf_test.c
+++ b/libsrc/tests/printf_test.c
@@ -104,6 +104,7 @@ TEST(vsnprintf) {
     EXPECT("PRIuMAX:18446744073709551615", "PRIuMAX:%" PRIuMAX, UINTMAX_MAX);
   }
   EXPECT("size_t:54321, ssize_t:-54321", "size_t:%zu, ssize_t:%zd", (size_t)54321, (ssize_t)-54321);
+  EXPECT("size_t:0x54321", "size_t:0x%zx", (size_t)0x54321);
   EXPECT("PRId64:1311768467463790320", "PRId64:%" PRId64, (int64_t)0x123456789abcdef0);
   EXPECT("PRIu64:18364758544493064720", "PRIu64:%" PRIu64, (uint64_t)0xfedcba9876543210);
 
diff --git a/src/wcc/emit_wasm.c b/src/wcc/emit_wasm.c
index 31d59c7f9..60b4735c8 100644
--- a/src/wcc/emit_wasm.c
+++ b/src/wcc/emit_wasm.c
@@ -505,7 +505,7 @@ static Vector *emit_data_section(EmitWasm *ew) {
       data_push(&datasec, 0);  // flags
       // Init (address).
       uint32_t address = segment->gvarinfo->non_prim.address;
-      VERBOSE("%04x: %.*s (size=%zu)\n", address, NAMES(segment->gvarinfo->varinfo->name),
+      VERBOSE("%04x: %.*s  (size=0x%zx)\n", address, NAMES(segment->gvarinfo->varinfo->name),
               type_size(segment->gvarinfo->varinfo->type));
       data_push(&datasec, OP_I32_CONST);
       data_leb128(&datasec, -1, address);
diff --git a/src/wcc/traverse.c b/src/wcc/traverse.c
index 4347d015c..67c54fde5 100644
--- a/src/wcc/traverse.c
+++ b/src/wcc/traverse.c
@@ -858,7 +858,7 @@ void traverse_ast(Vector *decls) {
         info->non_prim.address = address;
         size_t size = type_size(varinfo->type);
         address += size;
-        VERBOSE("%04x: %.*s  (size=0x%lx)\n", info->non_prim.address, NAMES(varinfo->name), size);
+        VERBOSE("%04x: %.*s  (size=0x%zx)\n", info->non_prim.address, NAMES(varinfo->name), size);
       }
     }
   }