diff --git a/NMSSH/NMSFTP.m b/NMSSH/NMSFTP.m
index fb19fae..89d259b 100644
--- a/NMSSH/NMSFTP.m
+++ b/NMSSH/NMSFTP.m
@@ -166,7 +166,7 @@ - (BOOL)removeFileAtPath:(NSString *)path {
 - (NSData *)contentsAtPath:(NSString *)path {
     LIBSSH2_SFTP_HANDLE *handle = libssh2_sftp_open(self.sftpSession, [path UTF8String], LIBSSH2_FXF_READ, 0);
 
-    char buffer[0x4000];
+    char buffer[kNMSSHBufferSize];
     long rc = libssh2_sftp_read(handle, buffer, (ssize_t)sizeof(buffer));
     libssh2_sftp_close(handle);
 
diff --git a/NMSSH/NMSSH.h b/NMSSH/NMSSH.h
index 9207354..a65a37e 100644
--- a/NMSSH/NMSSH.h
+++ b/NMSSH/NMSSH.h
@@ -5,6 +5,8 @@
 #import <sys/socket.h>
 #import <arpa/inet.h>
 
+#define kNMSSHBufferSize (5*1024*1024)
+
 @class NMSSHSession, NMSSHChannel, NMSFTP;
 
 #import "NMSSHSession.h"
diff --git a/NMSSH/NMSSHChannel.m b/NMSSH/NMSSHChannel.m
index 7c8a614..d1f8647 100644
--- a/NMSSH/NMSSHChannel.m
+++ b/NMSSH/NMSSHChannel.m
@@ -248,7 +248,7 @@ - (NSString *)execute:(NSString *)command error:(NSError *__autoreleasing *)erro
     NSMutableString *response = [[NSMutableString alloc] init];
     for (;;) {
         ssize_t rc;
-        char buffer[0x4000];
+        char buffer[kNMSSHBufferSize];
         char errorBuffer[0x4000];
 
         do {
@@ -379,7 +379,7 @@ - (BOOL)startShell:(NSError *__autoreleasing *)error  {
         for (;;) {
             ssize_t rc;
             ssize_t erc;
-            char buffer[0x4000];
+            char buffer[kNMSSHBufferSize];
             char errorBuffer[0x4000];
 
             do {
@@ -523,7 +523,7 @@ - (BOOL)uploadFile:(NSString *)localPath to:(NSString *)remotePath {
     [self setType:NMSSHChannelTypeSCP];
 
     // Wait for file transfer to finish
-    char mem[1024];
+    char mem[kNMSSHBufferSize];
     size_t nread;
     char *ptr;
     while ((nread = fread(mem, 1, sizeof(mem), local)) > 0) {
@@ -583,7 +583,7 @@ - (BOOL)downloadFile:(NSString *)remotePath to:(NSString *)localPath {
     // Save data to local file
     off_t got = 0;
     while (got < fileinfo.st_size) {
-        char mem[1024];
+        char mem[kNMSSHBufferSize];
         long long amount = sizeof(mem);
 
         if ((fileinfo.st_size - got) < amount) {