diff --git a/src/liblzma/common/block_header_decoder.c b/src/liblzma/common/block_header_decoder.c
index 1dd982f..730c524 100644
--- a/src/liblzma/common/block_header_decoder.c
+++ b/src/liblzma/common/block_header_decoder.c
@@ -67,8 +67,11 @@
 	const size_t in_size = block->header_size - 4;
 
 	// Verify CRC32
-	if (lzma_crc32(in, in_size, 0) != unaligned_read32le(in + in_size))
+	if (lzma_crc32(in, in_size, 0) != unaligned_read32le(in + in_size)) {
+#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
 		return LZMA_DATA_ERROR;
+#endif
+	}
 
 	// Check for unsupported flags.
 	if (in[1] & 0x3C)
diff --git a/src/liblzma/common/index_decoder.c b/src/liblzma/common/index_decoder.c
index e71fc6d..b268988 100644
--- a/src/liblzma/common/index_decoder.c
+++ b/src/liblzma/common/index_decoder.c
@@ -180,8 +180,11 @@
 				return LZMA_OK;
 
 			if (((coder->crc32 >> (coder->pos * 8)) & 0xFF)
-					!= in[(*in_pos)++])
+					!= in[(*in_pos)++]) {
+#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
 				return LZMA_DATA_ERROR;
+#endif
+			}
 
 		} while (++coder->pos < 4);
 
diff --git a/src/liblzma/common/index_hash.c b/src/liblzma/common/index_hash.c
index d7a0344..e131fab 100644
--- a/src/liblzma/common/index_hash.c
+++ b/src/liblzma/common/index_hash.c
@@ -313,8 +313,11 @@
 				return LZMA_OK;
 
 			if (((index_hash->crc32 >> (index_hash->pos * 8))
-					& 0xFF) != in[(*in_pos)++])
+					& 0xFF) != in[(*in_pos)++]) {
+#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
 				return LZMA_DATA_ERROR;
+#endif
+			}
 
 		} while (++index_hash->pos < 4);
 
diff --git a/src/liblzma/common/stream_flags_decoder.c b/src/liblzma/common/stream_flags_decoder.c
index 1bc2f97..84f9467 100644
--- a/src/liblzma/common/stream_flags_decoder.c
+++ b/src/liblzma/common/stream_flags_decoder.c
@@ -39,8 +39,11 @@
 	const uint32_t crc = lzma_crc32(in + sizeof(lzma_header_magic),
 			LZMA_STREAM_FLAGS_SIZE, 0);
 	if (crc != unaligned_read32le(in + sizeof(lzma_header_magic)
-			+ LZMA_STREAM_FLAGS_SIZE))
+			+ LZMA_STREAM_FLAGS_SIZE)) {
+#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
 		return LZMA_DATA_ERROR;
+#endif
+	}
 
 	// Stream Flags
 	if (stream_flags_decode(options, in + sizeof(lzma_header_magic)))
@@ -67,8 +70,11 @@
 	// CRC32
 	const uint32_t crc = lzma_crc32(in + sizeof(uint32_t),
 			sizeof(uint32_t) + LZMA_STREAM_FLAGS_SIZE, 0);
-	if (crc != unaligned_read32le(in))
+	if (crc != unaligned_read32le(in)) {
+#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
 		return LZMA_DATA_ERROR;
+#endif
+	}
 
 	// Stream Flags
 	if (stream_flags_decode(options, in + sizeof(uint32_t) * 2))