diff --git a/kitty/data-types.h b/kitty/data-types.h
index bb74c4ee0..6e877af45 100644
--- a/kitty/data-types.h
+++ b/kitty/data-types.h
@@ -368,5 +368,5 @@ void play_canberra_sound(const char *which_sound, const char *event_id, bool is_
 SPRITE_MAP_HANDLE alloc_sprite_map(unsigned int, unsigned int);
 SPRITE_MAP_HANDLE free_sprite_map(SPRITE_MAP_HANDLE);
 const char* get_hyperlink_for_id(const HYPERLINK_POOL_HANDLE, hyperlink_id_type id, bool only_url);
-
+bool copy_between_files(int infd, int outfd, off_t in_pos, size_t len, uint8_t *buf, size_t bufsz);
 void log_event(const char *format, ...) __attribute__((format(printf, 1, 2)));
diff --git a/kitty/disk-cache.c b/kitty/disk-cache.c
index 954229acb..099c70104 100644
--- a/kitty/disk-cache.c
+++ b/kitty/disk-cache.c
@@ -7,10 +7,6 @@
 
 #define EXTRA_INIT if (PyModule_AddFunctions(module, module_methods) != 0) return false;
 #define MAX_KEY_SIZE 256u
-#if __linux__
-#define HAS_SENDFILE
-#endif
-
 #include "disk-cache.h"
 #include "safe-wrappers.h"
 #include "kitty-uthash.h"
@@ -22,9 +18,6 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <time.h>
-#ifdef HAS_SENDFILE
-#include <sys/sendfile.h>
-#endif
 
 
 typedef struct {
@@ -113,57 +106,6 @@ open_cache_file(const char *cache_path) {
 }
 
 // Write loop {{{
-static bool
-copy_between_files(int infd, int outfd, off_t in_pos, size_t len, uint8_t *buf, size_t bufsz) {
-#ifdef HAS_SENDFILE
-    (void)buf; (void)bufsz;
-    unsigned num_of_consecutive_zero_returns = 128;
-    while (len) {
-        off_t r = in_pos;
-        ssize_t n = sendfile(outfd, infd, &r, len);
-        if (n < 0) {
-            if (errno != EAGAIN) return false;
-            continue;
-        }
-        if (n == 0) {
-            // happens if input file is truncated
-            if (!--num_of_consecutive_zero_returns) return false;
-            continue;
-        };
-        num_of_consecutive_zero_returns = 128;
-        in_pos += n; len -= n;
-    }
-#else
-    while (len) {
-        ssize_t amt_read = pread(infd, buf, MIN(len, bufsz), in_pos);
-        if (amt_read < 0) {
-            if (errno == EINTR || errno == EAGAIN) continue;
-            return false;
-        }
-        if (amt_read == 0) {
-            errno = EIO;
-            return false;
-        }
-        len -= amt_read;
-        in_pos += amt_read;
-        uint8_t *p = buf;
-        while(amt_read) {
-            ssize_t amt_written = write(outfd, p, amt_read);
-            if (amt_written < 0) {
-                if (errno == EINTR || errno == EAGAIN) continue;
-                return false;
-            }
-            if (amt_written == 0) {
-                errno = EIO;
-                return false;
-            }
-            amt_read -= amt_written;
-            p += amt_written;
-        }
-    }
-#endif
-    return true;
-}
 
 static off_t
 size_of_cache_file(DiskCache *self) {
diff --git a/kitty/fast-file-copy.c b/kitty/fast-file-copy.c
new file mode 100644
index 000000000..9105cdbc5
--- /dev/null
+++ b/kitty/fast-file-copy.c
@@ -0,0 +1,67 @@
+/*
+ * fast-file-copy.c
+ * Copyright (C) 2021 Kovid Goyal <kovid at kovidgoyal.net>
+ *
+ * Distributed under terms of the GPL3 license.
+ */
+
+#include "data-types.h"
+#if __linux__
+#define HAS_SENDFILE
+#endif
+
+#ifdef HAS_SENDFILE
+#include <sys/sendfile.h>
+#endif
+
+bool
+copy_between_files(int infd, int outfd, off_t in_pos, size_t len, uint8_t *buf, size_t bufsz) {
+#ifdef HAS_SENDFILE
+    (void)buf; (void)bufsz;
+    unsigned num_of_consecutive_zero_returns = 128;
+    while (len) {
+        off_t r = in_pos;
+        ssize_t n = sendfile(outfd, infd, &r, len);
+        if (n < 0) {
+            if (errno != EAGAIN) return false;
+            continue;
+        }
+        if (n == 0) {
+            // happens if input file is truncated
+            if (!--num_of_consecutive_zero_returns) return false;
+            continue;
+        };
+        num_of_consecutive_zero_returns = 128;
+        in_pos += n; len -= n;
+    }
+#else
+    while (len) {
+        ssize_t amt_read = pread(infd, buf, MIN(len, bufsz), in_pos);
+        if (amt_read < 0) {
+            if (errno == EINTR || errno == EAGAIN) continue;
+            return false;
+        }
+        if (amt_read == 0) {
+            errno = EIO;
+            return false;
+        }
+        len -= amt_read;
+        in_pos += amt_read;
+        uint8_t *p = buf;
+        while(amt_read) {
+            ssize_t amt_written = write(outfd, p, amt_read);
+            if (amt_written < 0) {
+                if (errno == EINTR || errno == EAGAIN) continue;
+                return false;
+            }
+            if (amt_written == 0) {
+                errno = EIO;
+                return false;
+            }
+            amt_read -= amt_written;
+            p += amt_written;
+        }
+    }
+#endif
+    return true;
+}