diff --git a/util/lar/stream.c b/util/lar/stream.c
index bf39473bf5..1818c539a2 100644
--- a/util/lar/stream.c
+++ b/util/lar/stream.c
@@ -846,7 +846,7 @@ int maxsize(struct lar *lar, char *name)
 
 /**
  * Compress an area according to an algorithm. If the area grows, 
- * use no compression. 
+ * use no compression.  The size of temp should be at least size bytes.
  * @param ptr data to be compressed
  * @param size size of the data 
  * @param temp destination of compressed data
diff --git a/util/lzma/minilzma.cc b/util/lzma/minilzma.cc
index cd68e387ca..7610910a19 100644
--- a/util/lzma/minilzma.cc
+++ b/util/lzma/minilzma.cc
@@ -283,11 +283,21 @@ int main(int argc, char *argv[])
 #else
 extern "C" {
 
+/**
+ * Compress a buffer with lzma
+ * Don't copy the result back if it is too large.
+ * @param in a pointer to the buffer
+ * @param in_len the length in bytes
+ * @param out a pointer to a buffer of at least size in_len
+ * @param out_len a pointer to the compressed length of in 
+ */
+
 void do_lzma_compress(char *in, int in_len, char *out, int *out_len) {
 	std::vector<unsigned char> result;
 	result = LZMACompress(std::vector<unsigned char>(in, in + in_len));
 	*out_len = result.size();
-	std::memcpy(out, &result[0], *out_len);
+	if (*out_len < in_len)
+		std::memcpy(out, &result[0], *out_len);
 }
 
 void do_lzma_uncompress(char *dst, int dst_len, char *src, int src_len) {
diff --git a/util/nrv2b/nrv2b.c b/util/nrv2b/nrv2b.c
index 52ef0d138c..832a20014c 100644
--- a/util/nrv2b/nrv2b.c
+++ b/util/nrv2b/nrv2b.c
@@ -1304,11 +1304,28 @@ void Encode(void)  /* compression */
 #endif
 
 #ifdef COMPACT
+
+/**
+ * Compress a buffer with nrv2b
+ * Don't copy the result back if it is too large
+ * @param in a pointer to the buffer
+ * @param in_len the length in bytes
+ * @param out a pointer to a buffer of at least size in_len
+ * @param out_len a pointer to the compressed length of in 
+ */
+
 void do_nrv2b_compress(uint8_t *in, int in_len, uint8_t *out, int *out_len) {
 	unsigned long new_out_len = in_len + (in_len/8) + 256;
-	out = malloc(new_out_len);
-	ucl_nrv2b_99_compress(in, in_len, out, &new_out_len, 0 );
+	uint8_t *new_out = malloc(new_out_len);
+	if (new_out == NULL) {
+		printf("Not enough memory to allocate buffer.\n");
+		exit(1);
+	}
+	ucl_nrv2b_99_compress(in, in_len, new_out, &new_out_len, 0 );
 	*out_len = (int) new_out_len;
+	if (*out_len < in_len)
+		memcpy(out, new_out, *out_len);
+	free(new_out);
 }
 #endif