diff --git a/configure.ac b/configure.ac
index b49fbc5..b51e1e1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -83,6 +83,7 @@ AM_CONDITIONAL([STATIC], [test "x$static" = "xyes"])
 AC_CHECK_HEADERS(fcntl.h sys/time.h unistd.h sys/mman.h)
 AC_CHECK_HEADERS(ctype.h errno.h sys/resource.h)
 AC_CHECK_HEADERS(endian.h sys/endian.h arpa/inet.h)
+AC_CHECK_HEADERS(alloca.h)
 
 AC_TYPE_OFF_T
 AC_TYPE_SIZE_T
diff --git a/lrzip_private.h b/lrzip_private.h
index 7eae476..716577e 100644
--- a/lrzip_private.h
+++ b/lrzip_private.h
@@ -20,6 +20,8 @@
 #ifndef LRZIP_PRIV_H
 #define LRZIP_PRIV_H
 
+#include "config.h"
+
 #define NUM_STREAMS 2
 #define STREAM_BUFSIZE (1024 * 1024 * 10)
 
@@ -117,6 +119,7 @@ extern int errno;
 
 #define likely(x)	__builtin_expect(!!(x), 1)
 #define unlikely(x)	__builtin_expect(!!(x), 0)
+#define __maybe_unused	__attribute__((unused))
 
 typedef long long int i64;
 typedef uint32_t u32;
diff --git a/lzma/C/LzFindMt.c b/lzma/C/LzFindMt.c
index aa41ed9..fa91234 100644
--- a/lzma/C/LzFindMt.c
+++ b/lzma/C/LzFindMt.c
@@ -5,6 +5,8 @@
 
 #include "LzFindMt.h"
 
+#include "lrzip.h"
+
 void MtSync_Construct(CMtSync *p)
 {
   p->wasCreated = False;
@@ -454,7 +456,7 @@ void MatchFinderMt_Destruct(CMatchFinderMt *p, ISzAlloc *alloc)
 static unsigned MY_STD_CALL HashThreadFunc2(void *p) { HashThreadFunc((CMatchFinderMt *)p);  return 0; }
 static unsigned MY_STD_CALL BtThreadFunc2(void *p)
 {
-  Byte allocaDummy[0x180];
+  __maybe_unused Byte allocaDummy[0x180];
   int i = 0;
   for (i = 0; i < 16; i++)
     allocaDummy[i] = (Byte)i;
diff --git a/lzma/C/LzmaEnc.c b/lzma/C/LzmaEnc.c
index cf13138..efd46c0 100644
--- a/lzma/C/LzmaEnc.c
+++ b/lzma/C/LzmaEnc.c
@@ -17,6 +17,8 @@
 #include "LzFindMt.h"
 #endif
 
+#include "lrzip.h"
+
 #ifdef SHOW_STAT
 static int ttt = 0;
 #endif
@@ -2156,7 +2158,7 @@ static SRes LzmaEnc_Encode2(CLzmaEnc *p, ICompressProgress *progress)
   SRes res = SZ_OK;
 
   #ifndef _7ZIP_ST
-  Byte allocaDummy[0x300];
+  __maybe_unused Byte allocaDummy[0x300];
   int i = 0;
   for (i = 0; i < 16; i++)
     allocaDummy[i] = (Byte)i;