diff --git a/src/literal.cc b/src/literal.cc
index b10b5ad43..a7edce94d 100644
--- a/src/literal.cc
+++ b/src/literal.cc
@@ -474,6 +474,10 @@ Result FloatParser<T>::Parse(LiteralType literal_type,
 // static
 template <typename T>
 void FloatWriter<T>::WriteHex(char* out, size_t size, Uint bits) {
+  if (size == 0) {
+    return;
+  }
+
   static constexpr int kNumNybbles = Traits::kBits / 4;
   static constexpr int kTopNybbleShift = Traits::kBits - 4;
   static constexpr Uint kTopNybble = Uint(0xf) << kTopNybbleShift;
@@ -811,6 +815,10 @@ void WriteDoubleHex(char* buffer, size_t size, uint64_t bits) {
 }
 
 void WriteUint128(char* buffer, size_t size, v128 bits) {
+  if (size == 0) {
+    return;
+  }
+
   uint64_t digits;
   uint64_t remainder;
   char reversed_buffer[40];
diff --git a/src/test-literal.cc b/src/test-literal.cc
index 4408f64e8..05da7338e 100644
--- a/src/test-literal.cc
+++ b/src/test-literal.cc
@@ -29,6 +29,16 @@ using namespace wabt;
 
 namespace {
 
+TEST(WriteHexTest, ZeroSizeDoesNotAccessOutput) {
+  char output = 'x';
+
+  WriteFloatHex(&output, 0, 0);
+  EXPECT_EQ('x', output);
+
+  WriteDoubleHex(&output, 0, 0);
+  EXPECT_EQ('x', output);
+}
+
 enum ParseIntTypeCombo {
   UnsignedOnly,
   SignedAndUnsigned,
@@ -853,6 +863,13 @@ TEST(WriteUint128, Basic) {
   AssertWriteUint128Equals({0, 0, 1, 0}, "18446744073709551616");
 }
 
+TEST(WriteUint128, ZeroSizeDoesNotAccessOutput) {
+  char output = 'x';
+
+  WriteUint128(&output, 0, {0, 0, 0, 0});
+  EXPECT_EQ('x', output);
+}
+
 TEST(WriteUint128, BufferTooSmall) {
   {
     char buffer[20];