diff --git a/lld/test/wasm/data-segments.ll b/lld/test/wasm/data-segments.ll
--- a/lld/test/wasm/data-segments.ll
+++ b/lld/test/wasm/data-segments.ll
@@ -222,7 +222,7 @@
 ; PIC-DIS-NEXT:        global.get      1
 ; PIC-DIS-NEXT:        [[PTR]].add
 ; DIS-NEXT:            i32.const       0
-; DIS-NEXT:            i32.const       10000
+; DIS-NEXT:            [[PTR]].const   10000
 ; DIS-NEXT:            memory.fill     0
 
 ; NOPIC-DIS-NEXT:      [[PTR]].const   11064
diff --git a/lld/wasm/Writer.cpp b/lld/wasm/Writer.cpp
--- a/lld/wasm/Writer.cpp
+++ b/lld/wasm/Writer.cpp
@@ -1226,7 +1226,7 @@
 
         if (s->isBss) {
           writeI32Const(os, 0, "fill value");
-          writeI32Const(os, s->size, "memory region size");
+          writePtrConst(os, s->size, is64, "memory region size");
           writeU8(os, WASM_OPCODE_MISC_PREFIX, "bulk-memory prefix");
           writeUleb128(os, WASM_OPCODE_MEMORY_FILL, "memory.fill");
           writeU8(os, 0, "memory index immediate");