diff --git a/src/credentials/CHIPCertFromX509.cpp b/src/credentials/CHIPCertFromX509.cpp
index 15cc47669511bf..099709facf0525 100644
--- a/src/credentials/CHIPCertFromX509.cpp
+++ b/src/credentials/CHIPCertFromX509.cpp
@@ -732,10 +732,7 @@ CHIP_ERROR ConvertX509CertsToChipCertArray(const ByteSpan & x509NOC, const ByteS
 
     TLVWriter writer;
 
-    // We can still generate the certificate if the output chip cert buffer is bigger than UINT32_MAX,
-    // since generated cert needs less space than UINT32_MAX.
-    uint32_t chipCertBufLen = (chipCertArray.size() > UINT32_MAX) ? UINT32_MAX : static_cast<uint32_t>(chipCertArray.size());
-    writer.Init(chipCertArray.data(), chipCertBufLen);
+    writer.Init(chipCertArray.data(), chipCertArray.size());
 
     TLVType outerContainer;
     ReturnErrorOnFailure(writer.StartContainer(AnonymousTag, kTLVType_Array, outerContainer));
@@ -767,7 +764,9 @@ CHIP_ERROR ConvertX509CertsToChipCertArray(const ByteSpan & x509NOC, const ByteS
     ReturnErrorOnFailure(writer.EndContainer(outerContainer));
     ReturnErrorOnFailure(writer.Finalize());
 
-    ReturnErrorCodeIf(writer.GetLengthWritten() > chipCertBufLen, CHIP_ERROR_INTERNAL);
+    // This error return is a bit weird... if we already overran our buffer,
+    // then fail???
+    ReturnErrorCodeIf(writer.GetLengthWritten() > chipCertArray.size(), CHIP_ERROR_INTERNAL);
     chipCertArray.reduce_size(writer.GetLengthWritten());
 
     return CHIP_NO_ERROR;
diff --git a/src/lib/core/CHIPTLV.h b/src/lib/core/CHIPTLV.h
index 680eb60872d944..e50c3b26f75d0a 100644
--- a/src/lib/core/CHIPTLV.h
+++ b/src/lib/core/CHIPTLV.h
@@ -114,7 +114,7 @@ class DLL_EXPORT TLVReader
      * @param[in]   dataLen The length of the TLV data to be parsed.
      *
      */
-    void Init(const uint8_t * data, uint32_t dataLen);
+    void Init(const uint8_t * data, size_t dataLen);
 
     /**
      * Initializes a TLVReader object to read from a TLVBackingStore.
@@ -849,7 +849,7 @@ class DLL_EXPORT TLVWriter
      * @param[in]   maxLen  The maximum number of bytes that should be written to the output buffer.
      *
      */
-    void Init(uint8_t * buf, uint32_t maxLen);
+    void Init(uint8_t * buf, size_t maxLen);
 
     /**
      * Initializes a TLVWriter object to write into memory provided by a TLVBackingStore.
diff --git a/src/lib/core/CHIPTLVReader.cpp b/src/lib/core/CHIPTLVReader.cpp
index d614493b38cf9f..42627d1cbd8550 100644
--- a/src/lib/core/CHIPTLVReader.cpp
+++ b/src/lib/core/CHIPTLVReader.cpp
@@ -38,13 +38,15 @@ using namespace chip::Encoding;
 
 static const uint8_t sTagSizes[] = { 0, 1, 2, 4, 2, 4, 6, 8 };
 
-void TLVReader::Init(const uint8_t * data, uint32_t dataLen)
-{
-    mBackingStore = nullptr;
-    mReadPoint    = data;
-    mBufEnd       = data + dataLen;
-    mLenRead      = 0;
-    mMaxLen       = dataLen;
+void TLVReader::Init(const uint8_t * data, size_t dataLen)
+{
+    // TODO: Maybe we can just make mMaxLen and mLenRead size_t instead?
+    uint32_t actualDataLen = dataLen > UINT32_MAX ? UINT32_MAX : static_cast<uint32_t>(dataLen);
+    mBackingStore          = nullptr;
+    mReadPoint             = data;
+    mBufEnd                = data + actualDataLen;
+    mLenRead               = 0;
+    mMaxLen                = actualDataLen;
     ClearElementState();
     mContainerType = kTLVType_NotSpecified;
     SetContainerOpen(false);
diff --git a/src/lib/core/CHIPTLVWriter.cpp b/src/lib/core/CHIPTLVWriter.cpp
index 1f09fee85fa372..514a0a335e8b81 100644
--- a/src/lib/core/CHIPTLVWriter.cpp
+++ b/src/lib/core/CHIPTLVWriter.cpp
@@ -48,13 +48,15 @@ namespace TLV {
 
 using namespace chip::Encoding;
 
-NO_INLINE void TLVWriter::Init(uint8_t * buf, uint32_t maxLen)
+NO_INLINE void TLVWriter::Init(uint8_t * buf, size_t maxLen)
 {
-    mBackingStore = nullptr;
+    // TODO: Maybe we can just make mMaxLen, mLenWritten, mRemainingLen size_t instead?
+    uint32_t actualMaxLen = maxLen > UINT32_MAX ? UINT32_MAX : static_cast<uint32_t>(maxLen);
+    mBackingStore         = nullptr;
     mBufStart = mWritePoint = buf;
-    mRemainingLen           = maxLen;
+    mRemainingLen           = actualMaxLen;
     mLenWritten             = 0;
-    mMaxLen                 = maxLen;
+    mMaxLen                 = actualMaxLen;
     mContainerType          = kTLVType_NotSpecified;
     SetContainerOpen(false);
     SetCloseContainerReserved(true);