diff --git a/src/Makefile b/src/Makefile
index 864f54b..61c5919 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2066,6 +2066,7 @@
 	test_channel \
 	test_charsearch \
 	test_cmdline \
+	test_crypt \
 	test_cscope \
 	test_cursor_func \
 	test_delete \
diff --git a/src/fileio.c b/src/fileio.c
index ea1f338..bcb8fef 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -3011,6 +3011,9 @@
 
 	    /* Remove cryptmethod specific header from the text. */
 	    header_len = crypt_get_header_len(method);
+	    if (*sizep <= header_len)
+		/* invalid header, buffer can't be encrypted */
+		return NULL;
 	    *filesizep += header_len;
 	    *sizep -= header_len;
 	    mch_memmove(ptr, ptr + header_len, (size_t)*sizep);
diff --git a/src/testdir/Make_all.mak b/src/testdir/Make_all.mak
index 65ad3ee..999f519 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -149,6 +149,7 @@
 	    test_channel.res \
 	    test_charsearch.res \
 	    test_cmdline.res \
+	    test_crypt.res \
 	    test_cscope.res \
 	    test_diffmode.res \
 	    test_digraph.res \
diff --git a/src/testdir/test_crypt.vim b/src/testdir/test_crypt.vim
new file mode 100644
index 0000000..10979dd
--- /dev/null
+++ b/src/testdir/test_crypt.vim
@@ -0,0 +1,42 @@
+" Tests for encryption.
+" TODO: include tests from test71.
+
+func Common_head_only(text)
+  " This was crashing Vim
+  split Xtest.txt
+  call setline(1, a:text)
+  wq
+  call feedkeys(":split Xtest.txt\<CR>foobar\<CR>", "tx")
+  call delete('Xtest.txt')
+  call assert_match('VimCrypt', getline(1))
+  bwipe!
+endfunc
+
+func Test_head_only_2()
+  call Common_head_only('VimCrypt~02!abc')
+endfunc
+
+func Test_head_only_3()
+  call Common_head_only('VimCrypt~03!abc')
+endfunc
+" Tests for encryption.
+" TODO: include tests from test71.
+
+func Common_head_only(text)
+  " This was crashing Vim
+  split Xtest.txt
+  call setline(1, a:text)
+  wq
+  call feedkeys(":split Xtest.txt\<CR>foobar\<CR>", "tx")
+  call delete('Xtest.txt')
+  call assert_match('VimCrypt', getline(1))
+  bwipe!
+endfunc
+
+func Test_head_only_2()
+  call Common_head_only('VimCrypt~02!abc')
+endfunc
+
+func Test_head_only_3()
+  call Common_head_only('VimCrypt~03!abc')
+endfunc
diff --git a/src/version.c b/src/version.c
index cf986e4..2a60f8b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    10,
+/**/
     9,
 /**/
     8,