diff --git a/core/io/compression.cpp b/core/io/compression.cpp
index 28a975e2c6e6..aeed0d272b69 100644
--- a/core/io/compression.cpp
+++ b/core/io/compression.cpp
@@ -47,12 +47,13 @@ static ZSTD_DCtx *current_zstd_d_ctx = nullptr;
 static bool current_zstd_long_distance_matching;
 static int current_zstd_window_log_size;
 
-int Compression::compress(uint8_t *p_dst, const uint8_t *p_src, int p_src_size, Mode p_mode) {
+int64_t Compression::compress(uint8_t *p_dst, const uint8_t *p_src, int64_t p_src_size, Mode p_mode) {
 	switch (p_mode) {
 		case MODE_BROTLI: {
 			ERR_FAIL_V_MSG(-1, "Only brotli decompression is supported.");
 		} break;
 		case MODE_FASTLZ: {
+			ERR_FAIL_COND_V_MSG(p_src_size > INT32_MAX, -1, "Cannot compress a FastLZ/LZ77 file 2 GiB or larger. LZ77 supports larger files, but FastLZ's implementation uses C++ `int` so is limited to 2 GiB. Consider using Zstd instead.");
 			if (p_src_size < 16) {
 				uint8_t src[16];
 				memset(&src[p_src_size], 0, 16 - p_src_size);
@@ -65,6 +66,7 @@ int Compression::compress(uint8_t *p_dst, const uint8_t *p_src, int p_src_size,
 		} break;
 		case MODE_DEFLATE:
 		case MODE_GZIP: {
+			ERR_FAIL_COND_V_MSG(p_src_size > INT32_MAX, -1, "Cannot compress a Deflate or GZip file 2 GiB or larger. Deflate and GZip are both limited to 4 GiB, and ZLib's implementation uses C++ `int` so is limited to 2 GiB. Consider using Zstd instead.");
 			int window_bits = p_mode == MODE_DEFLATE ? 15 : 15 + 16;
 
 			z_stream strm;
@@ -95,22 +97,23 @@ int Compression::compress(uint8_t *p_dst, const uint8_t *p_src, int p_src_size,
 				ZSTD_CCtx_setParameter(cctx, ZSTD_c_enableLongDistanceMatching, 1);
 				ZSTD_CCtx_setParameter(cctx, ZSTD_c_windowLog, zstd_window_log_size);
 			}
-			int max_dst_size = get_max_compressed_buffer_size(p_src_size, MODE_ZSTD);
-			int ret = ZSTD_compressCCtx(cctx, p_dst, max_dst_size, p_src, p_src_size, zstd_level);
+			const int64_t max_dst_size = get_max_compressed_buffer_size(p_src_size, MODE_ZSTD);
+			const size_t ret = ZSTD_compressCCtx(cctx, p_dst, max_dst_size, p_src, p_src_size, zstd_level);
 			ZSTD_freeCCtx(cctx);
-			return ret;
+			return (int64_t)ret;
 		} break;
 	}
 
 	ERR_FAIL_V(-1);
 }
 
-int Compression::get_max_compressed_buffer_size(int p_src_size, Mode p_mode) {
+int64_t Compression::get_max_compressed_buffer_size(int64_t p_src_size, Mode p_mode) {
 	switch (p_mode) {
 		case MODE_BROTLI: {
 			ERR_FAIL_V_MSG(-1, "Only brotli decompression is supported.");
 		} break;
 		case MODE_FASTLZ: {
+			ERR_FAIL_COND_V_MSG(p_src_size > INT32_MAX, -1, "Cannot compress a FastLZ/LZ77 file 2 GiB or larger. LZ77 supports larger files, but FastLZ's implementation uses C++ `int` so is limited to 2 GiB. Consider using Zstd instead.");
 			int ss = p_src_size + p_src_size * 6 / 100;
 			if (ss < 66) {
 				ss = 66;
@@ -120,6 +123,7 @@ int Compression::get_max_compressed_buffer_size(int p_src_size, Mode p_mode) {
 		} break;
 		case MODE_DEFLATE:
 		case MODE_GZIP: {
+			ERR_FAIL_COND_V_MSG(p_src_size > INT32_MAX, -1, "Cannot compress a Deflate or GZip file 2 GiB or larger. Deflate and GZip are both limited to 4 GiB, and ZLib's implementation uses C++ `int` so is limited to 2 GiB. Consider using Zstd instead.");
 			int window_bits = p_mode == MODE_DEFLATE ? 15 : 15 + 16;
 
 			z_stream strm;
@@ -142,7 +146,7 @@ int Compression::get_max_compressed_buffer_size(int p_src_size, Mode p_mode) {
 	ERR_FAIL_V(-1);
 }
 
-int Compression::decompress(uint8_t *p_dst, int p_dst_max_size, const uint8_t *p_src, int p_src_size, Mode p_mode) {
+int64_t Compression::decompress(uint8_t *p_dst, int64_t p_dst_max_size, const uint8_t *p_src, int64_t p_src_size, Mode p_mode) {
 	switch (p_mode) {
 		case MODE_BROTLI: {
 #ifdef BROTLI_ENABLED
@@ -155,6 +159,7 @@ int Compression::decompress(uint8_t *p_dst, int p_dst_max_size, const uint8_t *p
 #endif
 		} break;
 		case MODE_FASTLZ: {
+			ERR_FAIL_COND_V_MSG(p_dst_max_size > INT32_MAX, -1, "Cannot decompress a FastLZ/LZ77 file 2 GiB or larger. LZ77 supports larger files, but FastLZ's implementation uses C++ `int` so is limited to 2 GiB. Consider using Zstd instead.");
 			int ret_size = 0;
 
 			if (p_dst_max_size < 16) {
@@ -169,6 +174,7 @@ int Compression::decompress(uint8_t *p_dst, int p_dst_max_size, const uint8_t *p
 		} break;
 		case MODE_DEFLATE:
 		case MODE_GZIP: {
+			ERR_FAIL_COND_V_MSG(p_dst_max_size > INT32_MAX, -1, "Cannot decompress a Deflate or GZip file 2 GiB or larger. Deflate and GZip are both limited to 4 GiB, and ZLib's implementation uses C++ `int` so is limited to 2 GiB. Consider using Zstd instead.");
 			int window_bits = p_mode == MODE_DEFLATE ? 15 : 15 + 16;
 
 			z_stream strm;
@@ -207,8 +213,8 @@ int Compression::decompress(uint8_t *p_dst, int p_dst_max_size, const uint8_t *p
 				current_zstd_window_log_size = zstd_window_log_size;
 			}
 
-			int ret = ZSTD_decompressDCtx(current_zstd_d_ctx, p_dst, p_dst_max_size, p_src, p_src_size);
-			return ret;
+			size_t ret = ZSTD_decompressDCtx(current_zstd_d_ctx, p_dst, p_dst_max_size, p_src, p_src_size);
+			return (int64_t)ret;
 		} break;
 	}
 
@@ -220,7 +226,7 @@ int Compression::decompress(uint8_t *p_dst, int p_dst_max_size, const uint8_t *p
 	This is required for compressed data whose final uncompressed size is unknown, as is the case for HTTP response bodies.
 	This is much slower however than using Compression::decompress because it may result in multiple full copies of the output buffer.
 */
-int Compression::decompress_dynamic(Vector<uint8_t> *p_dst_vect, int p_max_dst_size, const uint8_t *p_src, int p_src_size, Mode p_mode) {
+int Compression::decompress_dynamic(Vector<uint8_t> *p_dst_vect, int64_t p_max_dst_size, const uint8_t *p_src, int64_t p_src_size, Mode p_mode) {
 	uint8_t *dst = nullptr;
 	int out_mark = 0;
 
diff --git a/core/io/compression.h b/core/io/compression.h
index a55c7c80d059..bb3f81f58d0b 100644
--- a/core/io/compression.h
+++ b/core/io/compression.h
@@ -52,8 +52,8 @@ class Compression {
 		MODE_BROTLI
 	};
 
-	static int compress(uint8_t *p_dst, const uint8_t *p_src, int p_src_size, Mode p_mode = MODE_ZSTD);
-	static int get_max_compressed_buffer_size(int p_src_size, Mode p_mode = MODE_ZSTD);
-	static int decompress(uint8_t *p_dst, int p_dst_max_size, const uint8_t *p_src, int p_src_size, Mode p_mode = MODE_ZSTD);
-	static int decompress_dynamic(Vector<uint8_t> *p_dst_vect, int p_max_dst_size, const uint8_t *p_src, int p_src_size, Mode p_mode);
+	static int64_t compress(uint8_t *p_dst, const uint8_t *p_src, int64_t p_src_size, Mode p_mode = MODE_ZSTD);
+	static int64_t get_max_compressed_buffer_size(int64_t p_src_size, Mode p_mode = MODE_ZSTD);
+	static int64_t decompress(uint8_t *p_dst, int64_t p_dst_max_size, const uint8_t *p_src, int64_t p_src_size, Mode p_mode = MODE_ZSTD);
+	static int decompress_dynamic(Vector<uint8_t> *p_dst_vect, int64_t p_max_dst_size, const uint8_t *p_src, int64_t p_src_size, Mode p_mode);
 };
diff --git a/core/io/file_access_compressed.cpp b/core/io/file_access_compressed.cpp
index da313492897d..892a66bc7c60 100644
--- a/core/io/file_access_compressed.cpp
+++ b/core/io/file_access_compressed.cpp
@@ -68,7 +68,7 @@ Error FileAccessCompressed::open_after_magic(Ref<FileAccess> p_base) {
 	read_block_count = bc;
 	read_block_size = read_blocks.size() == 1 ? read_total : block_size;
 
-	int ret = Compression::decompress(buffer.ptrw(), read_block_size, comp_buffer.ptr(), read_blocks[0].csize, cmode);
+	const int64_t ret = Compression::decompress(buffer.ptrw(), read_block_size, comp_buffer.ptr(), read_blocks[0].csize, cmode);
 	read_block = 0;
 	read_pos = 0;
 
@@ -137,10 +137,11 @@ void FileAccessCompressed::_close() {
 
 			Vector<uint8_t> cblock;
 			cblock.resize(Compression::get_max_compressed_buffer_size(bl, cmode));
-			int s = Compression::compress(cblock.ptrw(), bp, bl, cmode);
+			const int64_t compressed_size = Compression::compress(cblock.ptrw(), bp, bl, cmode);
+			ERR_FAIL_COND_MSG(compressed_size < 0, "FileAccessCompressed: Error compressing data.");
 
-			f->store_buffer(cblock.ptr(), s);
-			block_sizes.push_back(s);
+			f->store_buffer(cblock.ptr(), (uint64_t)compressed_size);
+			block_sizes.push_back(compressed_size);
 		}
 
 		f->seek(16); //ok write block sizes
@@ -200,7 +201,7 @@ void FileAccessCompressed::seek(uint64_t p_position) {
 				read_block = block_idx;
 				f->seek(read_blocks[read_block].offset);
 				f->get_buffer(comp_buffer.ptrw(), read_blocks[read_block].csize);
-				int ret = Compression::decompress(buffer.ptrw(), read_blocks.size() == 1 ? read_total : block_size, comp_buffer.ptr(), read_blocks[read_block].csize, cmode);
+				const int64_t ret = Compression::decompress(buffer.ptrw(), read_blocks.size() == 1 ? read_total : block_size, comp_buffer.ptr(), read_blocks[read_block].csize, cmode);
 				ERR_FAIL_COND_MSG(ret == -1, "Compressed file is corrupt.");
 				read_block_size = read_block == read_block_count - 1 ? read_total % block_size : block_size;
 			}
@@ -288,7 +289,7 @@ uint64_t FileAccessCompressed::get_buffer(uint8_t *p_dst, uint64_t p_length) con
 
 		// Read the next block of compressed data.
 		f->get_buffer(comp_buffer.ptrw(), read_blocks[read_block].csize);
-		int ret = Compression::decompress(buffer.ptrw(), read_blocks.size() == 1 ? read_total : block_size, comp_buffer.ptr(), read_blocks[read_block].csize, cmode);
+		const int64_t ret = Compression::decompress(buffer.ptrw(), read_blocks.size() == 1 ? read_total : block_size, comp_buffer.ptr(), read_blocks[read_block].csize, cmode);
 		ERR_FAIL_COND_V_MSG(ret == -1, -1, "Compressed file is corrupt.");
 		read_block_size = read_block == read_block_count - 1 ? read_total % block_size : block_size;
 		read_pos = 0;
diff --git a/core/io/remote_filesystem_client.cpp b/core/io/remote_filesystem_client.cpp
index 8467b75e7920..e542111588d3 100644
--- a/core/io/remote_filesystem_client.cpp
+++ b/core/io/remote_filesystem_client.cpp
@@ -215,7 +215,7 @@ Error RemoteFilesystemClient::_synchronize_with_server(const String &p_host, int
 	Vector<uint8_t> file_cache_buffer;
 	if (file_cache.size()) {
 		StringBuilder sbuild;
-		for (int i = 0; i < file_cache.size(); i++) {
+		for (int64_t i = 0; i < file_cache.size(); i++) {
 			sbuild.append(file_cache[i].path);
 			sbuild.append("::");
 			sbuild.append(itos(file_cache[i].server_modified_time));
@@ -224,7 +224,7 @@ Error RemoteFilesystemClient::_synchronize_with_server(const String &p_host, int
 		String s = sbuild.as_string();
 		CharString cs = s.utf8();
 		file_cache_buffer.resize(Compression::get_max_compressed_buffer_size(cs.length(), Compression::MODE_ZSTD));
-		int res_len = Compression::compress(file_cache_buffer.ptrw(), (const uint8_t *)cs.ptr(), cs.length(), Compression::MODE_ZSTD);
+		const int64_t res_len = Compression::compress(file_cache_buffer.ptrw(), (const uint8_t *)cs.ptr(), cs.length(), Compression::MODE_ZSTD);
 		file_cache_buffer.resize(res_len);
 
 		tcp_client->put_32(cs.length()); // Size of buffer uncompressed
diff --git a/core/variant/variant_call.cpp b/core/variant/variant_call.cpp
index 1ad69b4afb8d..16c885c8a734 100644
--- a/core/variant/variant_call.cpp
+++ b/core/variant/variant_call.cpp
@@ -799,7 +799,7 @@ struct _VariantCall {
 		if (p_instance->size() > 0) {
 			Compression::Mode mode = (Compression::Mode)(p_mode);
 			compressed.resize(Compression::get_max_compressed_buffer_size(p_instance->size(), mode));
-			int result = Compression::compress(compressed.ptrw(), p_instance->ptr(), p_instance->size(), mode);
+			int64_t result = Compression::compress(compressed.ptrw(), p_instance->ptr(), p_instance->size(), mode);
 
 			result = result >= 0 ? result : 0;
 			compressed.resize(result);
@@ -822,7 +822,7 @@ struct _VariantCall {
 		}
 
 		decompressed.resize(buffer_size);
-		int result = Compression::decompress(decompressed.ptrw(), buffer_size, p_instance->ptr(), p_instance->size(), mode);
+		int64_t result = Compression::decompress(decompressed.ptrw(), buffer_size, p_instance->ptr(), p_instance->size(), mode);
 
 		result = result >= 0 ? result : 0;
 		decompressed.resize(result);
diff --git a/editor/debugger/editor_file_server.cpp b/editor/debugger/editor_file_server.cpp
index 5fc5d7348370..b4673961a9ac 100644
--- a/editor/debugger/editor_file_server.cpp
+++ b/editor/debugger/editor_file_server.cpp
@@ -173,7 +173,8 @@ void EditorFileServer::poll() {
 
 		ERR_FAIL_COND(err != OK);
 		// Decompress the text with all the files
-		Compression::decompress(file_buffer_decompressed.ptr(), file_buffer_decompressed.size(), file_buffer.ptr(), file_buffer.size(), Compression::MODE_ZSTD);
+		const int64_t decompressed_size = Compression::decompress(file_buffer_decompressed.ptr(), file_buffer_decompressed.size(), file_buffer.ptr(), file_buffer.size(), Compression::MODE_ZSTD);
+		ERR_FAIL_COND_MSG(decompressed_size != file_buffer_decompressed.size(), "Error decompressing file buffer. Decompressed size did not match the expected size.");
 		String files_text = String::utf8((const char *)file_buffer_decompressed.ptr(), file_buffer_decompressed.size());
 		Vector<String> files = files_text.split("\n");
 
diff --git a/editor/doc_tools.cpp b/editor/doc_tools.cpp
index 9a5f8efcfb5d..e15519c07a33 100644
--- a/editor/doc_tools.cpp
+++ b/editor/doc_tools.cpp
@@ -1798,10 +1798,10 @@ Error DocTools::save_classes(const String &p_default_path, const HashMap<String,
 	return OK;
 }
 
-Error DocTools::load_compressed(const uint8_t *p_data, int p_compressed_size, int p_uncompressed_size) {
+Error DocTools::load_compressed(const uint8_t *p_data, int64_t p_compressed_size, int64_t p_uncompressed_size) {
 	Vector<uint8_t> data;
 	data.resize(p_uncompressed_size);
-	int ret = Compression::decompress(data.ptrw(), p_uncompressed_size, p_data, p_compressed_size, Compression::MODE_DEFLATE);
+	const int64_t ret = Compression::decompress(data.ptrw(), p_uncompressed_size, p_data, p_compressed_size, Compression::MODE_DEFLATE);
 	ERR_FAIL_COND_V_MSG(ret == -1, ERR_FILE_CORRUPT, "Compressed file is corrupt.");
 	class_list.clear();
 
@@ -1816,7 +1816,7 @@ Error DocTools::load_compressed(const uint8_t *p_data, int p_compressed_size, in
 	return OK;
 }
 
-Error DocTools::load_xml(const uint8_t *p_data, int p_size) {
+Error DocTools::load_xml(const uint8_t *p_data, int64_t p_size) {
 	Ref<XMLParser> parser = memnew(XMLParser);
 	Error err = parser->_open_buffer(p_data, p_size);
 	if (err) {
diff --git a/editor/doc_tools.h b/editor/doc_tools.h
index fcac2c2142c7..b66ce59c6b0e 100644
--- a/editor/doc_tools.h
+++ b/editor/doc_tools.h
@@ -55,6 +55,6 @@ class DocTools {
 	Error save_classes(const String &p_default_path, const HashMap<String, String> &p_class_path, bool p_use_relative_schema = true);
 
 	Error _load(Ref<XMLParser> parser);
-	Error load_compressed(const uint8_t *p_data, int p_compressed_size, int p_uncompressed_size);
-	Error load_xml(const uint8_t *p_data, int p_size);
+	Error load_compressed(const uint8_t *p_data, int64_t p_compressed_size, int64_t p_uncompressed_size);
+	Error load_xml(const uint8_t *p_data, int64_t p_size);
 };
diff --git a/editor/editor_translation.cpp b/editor/editor_translation.cpp
index fb59288e6efa..7d70cd26ac63 100644
--- a/editor/editor_translation.cpp
+++ b/editor/editor_translation.cpp
@@ -61,7 +61,7 @@ void load_editor_translations(const String &p_locale) {
 		if (etl->lang == p_locale) {
 			Vector<uint8_t> data;
 			data.resize(etl->uncomp_size);
-			int ret = Compression::decompress(data.ptrw(), etl->uncomp_size, etl->data, etl->comp_size, Compression::MODE_DEFLATE);
+			const int64_t ret = Compression::decompress(data.ptrw(), etl->uncomp_size, etl->data, etl->comp_size, Compression::MODE_DEFLATE);
 			ERR_FAIL_COND_MSG(ret == -1, "Compressed file is corrupt.");
 
 			Ref<FileAccessMemory> fa;
@@ -89,7 +89,7 @@ void load_property_translations(const String &p_locale) {
 		if (etl->lang == p_locale) {
 			Vector<uint8_t> data;
 			data.resize(etl->uncomp_size);
-			int ret = Compression::decompress(data.ptrw(), etl->uncomp_size, etl->data, etl->comp_size, Compression::MODE_DEFLATE);
+			const int64_t ret = Compression::decompress(data.ptrw(), etl->uncomp_size, etl->data, etl->comp_size, Compression::MODE_DEFLATE);
 			ERR_FAIL_COND_MSG(ret == -1, "Compressed file is corrupt.");
 
 			Ref<FileAccessMemory> fa;
@@ -117,7 +117,7 @@ void load_doc_translations(const String &p_locale) {
 		if (dtl->lang == p_locale) {
 			Vector<uint8_t> data;
 			data.resize(dtl->uncomp_size);
-			int ret = Compression::decompress(data.ptrw(), dtl->uncomp_size, dtl->data, dtl->comp_size, Compression::MODE_DEFLATE);
+			const int64_t ret = Compression::decompress(data.ptrw(), dtl->uncomp_size, dtl->data, dtl->comp_size, Compression::MODE_DEFLATE);
 			ERR_FAIL_COND_MSG(ret == -1, "Compressed file is corrupt.");
 
 			Ref<FileAccessMemory> fa;
@@ -145,7 +145,7 @@ void load_extractable_translations(const String &p_locale) {
 		if (etl->lang == p_locale) {
 			Vector<uint8_t> data;
 			data.resize(etl->uncomp_size);
-			int ret = Compression::decompress(data.ptrw(), etl->uncomp_size, etl->data, etl->comp_size, Compression::MODE_DEFLATE);
+			const int64_t ret = Compression::decompress(data.ptrw(), etl->uncomp_size, etl->data, etl->comp_size, Compression::MODE_DEFLATE);
 			ERR_FAIL_COND_MSG(ret == -1, "Compressed file is corrupt.");
 
 			Ref<FileAccessMemory> fa;
@@ -177,7 +177,7 @@ Vector<Vector<String>> get_extractable_message_list() {
 
 		Vector<uint8_t> data;
 		data.resize(etl->uncomp_size);
-		int ret = Compression::decompress(data.ptrw(), etl->uncomp_size, etl->data, etl->comp_size, Compression::MODE_DEFLATE);
+		const int64_t ret = Compression::decompress(data.ptrw(), etl->uncomp_size, etl->data, etl->comp_size, Compression::MODE_DEFLATE);
 		ERR_FAIL_COND_V_MSG(ret == -1, list, "Compressed file is corrupt.");
 
 		Ref<FileAccessMemory> fa;
diff --git a/modules/enet/enet_connection.cpp b/modules/enet/enet_connection.cpp
index db0faf2e02de..3c4f229ab359 100644
--- a/modules/enet/enet_connection.cpp
+++ b/modules/enet/enet_connection.cpp
@@ -422,11 +422,11 @@ size_t ENetConnection::Compressor::enet_compress(void *context, const ENetBuffer
 		compressor->src_mem.resize(inLimit);
 	}
 
-	int total = inLimit;
-	int ofs = 0;
+	size_t total = inLimit;
+	size_t ofs = 0;
 	while (total) {
 		for (size_t i = 0; i < inBufferCount; i++) {
-			int to_copy = MIN(total, int(inBuffers[i].dataLength));
+			const size_t to_copy = MIN(total, inBuffers[i].dataLength);
 			memcpy(&compressor->src_mem.write[ofs], inBuffers[i].data, to_copy);
 			ofs += to_copy;
 			total -= to_copy;
@@ -450,28 +450,29 @@ size_t ENetConnection::Compressor::enet_compress(void *context, const ENetBuffer
 		}
 	}
 
-	int req_size = Compression::get_max_compressed_buffer_size(ofs, mode);
+	const int64_t req_size = Compression::get_max_compressed_buffer_size(ofs, mode);
 	if (compressor->dst_mem.size() < req_size) {
 		compressor->dst_mem.resize(req_size);
 	}
-	int ret = Compression::compress(compressor->dst_mem.ptrw(), compressor->src_mem.ptr(), ofs, mode);
+	const int64_t ret = Compression::compress(compressor->dst_mem.ptrw(), compressor->src_mem.ptr(), ofs, mode);
 
 	if (ret < 0) {
 		return 0;
 	}
 
-	if (ret > int(outLimit)) {
+	const size_t ret_size = size_t(ret);
+	if (ret_size > outLimit) {
 		return 0; // Do not bother
 	}
 
-	memcpy(outData, compressor->dst_mem.ptr(), ret);
+	memcpy(outData, compressor->dst_mem.ptr(), ret_size);
 
 	return ret;
 }
 
 size_t ENetConnection::Compressor::enet_decompress(void *context, const enet_uint8 *inData, size_t inLimit, enet_uint8 *outData, size_t outLimit) {
 	Compressor *compressor = (Compressor *)(context);
-	int ret = -1;
+	int64_t ret = -1;
 	switch (compressor->mode) {
 		case COMPRESS_FASTLZ: {
 			ret = Compression::decompress(outData, outLimit, inData, inLimit, Compression::MODE_FASTLZ);
diff --git a/modules/gdscript/gdscript_tokenizer_buffer.cpp b/modules/gdscript/gdscript_tokenizer_buffer.cpp
index d9b6ec68a2c5..7f82ed5e6166 100644
--- a/modules/gdscript/gdscript_tokenizer_buffer.cpp
+++ b/modules/gdscript/gdscript_tokenizer_buffer.cpp
@@ -152,7 +152,7 @@ Error GDScriptTokenizerBuffer::set_code_buffer(const Vector<uint8_t> &p_buffer)
 		contents = p_buffer.slice(12);
 	} else {
 		contents.resize(decompressed_size);
-		int result = Compression::decompress(contents.ptrw(), contents.size(), &buf[12], p_buffer.size() - 12, Compression::MODE_ZSTD);
+		const int64_t result = Compression::decompress(contents.ptrw(), contents.size(), &buf[12], p_buffer.size() - 12, Compression::MODE_ZSTD);
 		ERR_FAIL_COND_V_MSG(result != decompressed_size, ERR_INVALID_DATA, "Error decompressing GDScript tokenizer buffer.");
 	}
 
@@ -371,10 +371,10 @@ Vector<uint8_t> GDScriptTokenizerBuffer::parse_code_string(const String &p_code,
 		case COMPRESS_ZSTD: {
 			encode_uint32(contents.size(), &buf.write[8]);
 			Vector<uint8_t> compressed;
-			int max_size = Compression::get_max_compressed_buffer_size(contents.size(), Compression::MODE_ZSTD);
+			const int64_t max_size = Compression::get_max_compressed_buffer_size(contents.size(), Compression::MODE_ZSTD);
 			compressed.resize(max_size);
 
-			int compressed_size = Compression::compress(compressed.ptrw(), contents.ptr(), contents.size(), Compression::MODE_ZSTD);
+			const int64_t compressed_size = Compression::compress(compressed.ptrw(), contents.ptr(), contents.size(), Compression::MODE_ZSTD);
 			ERR_FAIL_COND_V_MSG(compressed_size < 0, Vector<uint8_t>(), "Error compressing GDScript tokenizer buffer.");
 			compressed.resize(compressed_size);
 
diff --git a/modules/mbedtls/crypto_mbedtls.cpp b/modules/mbedtls/crypto_mbedtls.cpp
index 0bfdbac3b617..127504bfd105 100644
--- a/modules/mbedtls/crypto_mbedtls.cpp
+++ b/modules/mbedtls/crypto_mbedtls.cpp
@@ -371,7 +371,8 @@ void CryptoMbedTLS::load_default_certificates(const String &p_path) {
 			// Use builtin certs if there are no system certs.
 			PackedByteArray certs;
 			certs.resize(_certs_uncompressed_size + 1);
-			Compression::decompress(certs.ptrw(), _certs_uncompressed_size, _certs_compressed, _certs_compressed_size, Compression::MODE_DEFLATE);
+			const int64_t decompressed_size = Compression::decompress(certs.ptrw(), _certs_uncompressed_size, _certs_compressed, _certs_compressed_size, Compression::MODE_DEFLATE);
+			ERR_FAIL_COND_MSG(decompressed_size != _certs_uncompressed_size, "Error decompressing builtin CA certificates. Decompressed size did not match expected size.");
 			certs.write[_certs_uncompressed_size] = 0; // Make sure it ends with string terminator
 			default_certs->load_from_memory(certs.ptr(), certs.size());
 			print_verbose("Loaded builtin CA certificates");
diff --git a/servers/rendering/rendering_shader_container.cpp b/servers/rendering/rendering_shader_container.cpp
index fdc8b334d681..24bce006962a 100644
--- a/servers/rendering/rendering_shader_container.cpp
+++ b/servers/rendering/rendering_shader_container.cpp
@@ -422,10 +422,10 @@ bool RenderingShaderContainer::compress_code(const uint8_t *p_decompressed_bytes
 	*r_compressed_flags = 0;
 
 	PackedByteArray zstd_bytes;
-	int zstd_max_bytes = Compression::get_max_compressed_buffer_size(p_decompressed_size, Compression::MODE_ZSTD);
+	const int64_t zstd_max_bytes = Compression::get_max_compressed_buffer_size(p_decompressed_size, Compression::MODE_ZSTD);
 	zstd_bytes.resize(zstd_max_bytes);
 
-	int zstd_size = Compression::compress(zstd_bytes.ptrw(), p_decompressed_bytes, p_decompressed_size, Compression::MODE_ZSTD);
+	const int64_t zstd_size = Compression::compress(zstd_bytes.ptrw(), p_decompressed_bytes, p_decompressed_size, Compression::MODE_ZSTD);
 	if (zstd_size > 0 && (uint32_t)(zstd_size) < p_decompressed_size) {
 		// Only choose Zstd if it results in actual compression.
 		memcpy(p_compressed_bytes, zstd_bytes.ptr(), zstd_size);