diff --git a/src/std/c_file.c b/src/std/c_file.c
index 07bfa71989..228b3789bb 100644
--- a/src/std/c_file.c
+++ b/src/std/c_file.c
@@ -30,6 +30,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <string.h>
 
 #include "c_file.h"
 #include "c_string.h"
@@ -166,34 +167,38 @@ out:
 int c_compare_file( const char *f1, const char *f2 ) {
   _TCHAR *wf1, *wf2;
   int fd1 = -1, fd2 = -1;
-  size_t size1, size2, i;
+  size_t size1, size2;
   char buffer1[BUFFER_SIZE];
   char buffer2[BUFFER_SIZE];
   csync_stat_t stat1;
   csync_stat_t stat2;
 
-  register const char *s1;
-  register const char *s2;
-  int re = -1;
+  int rc = -1;
 
-  if( ! (f1 && f2) ) return -1;
+  if(f1 == NULL || f2 == NULL) return -1;
 
   wf1 = c_multibyte(f1);
+  if(wf1 == NULL) {
+    return -1;
+  }
   wf2 = c_multibyte(f2);
+  if(wf2 == NULL) {
+    return -1;
+  }
 
   /* compare size first. */
-  if( _tstat(wf1, &stat1) < 0 ) {
-    re = -1;
+  rc = _tstat(wf1, &stat1);
+  if(rc< 0) {
     goto out;
   }
-  if( _tstat(wf2, &stat2) < 0 ) {
-    re = -1;
+  rc = _tstat(wf2, &stat2);
+  if(rc < 0) {
     goto out;
   }
 
   /* if sizes are different, the files can not be equal. */
   if( stat1.st_size != stat2.st_size ) {
-    re = 0;
+    rc = 0;
     goto out;
   }
 
@@ -202,10 +207,13 @@ int c_compare_file( const char *f1, const char *f2 ) {
 #endif
 
   fd1 = _topen(wf1, O_RDONLY);
+  if(fd1 < 0) {
+    rc = -1;
+    goto out;
+  }
   fd2 = _topen(wf2, O_RDONLY);
-
-  if( !(fd1 > -1 && fd2 > -1)) {
-    re = -1;
+  if(fd2 < 0) {
+    rc = -1;
     goto out;
   }
 
@@ -213,30 +221,26 @@ int c_compare_file( const char *f1, const char *f2 ) {
     size2 = read( fd2, buffer2, BUFFER_SIZE );
 
     if( size1 != size2 ) {
-      re = 0;
+      rc = 0;
       goto out;
     }
-    s1 = buffer1;
-    s2 = buffer2;
-
-    for( i = 0; i < size1; i++ ) {
-      if( *s1++ != *s2++ ) {
-        re = 0;
-        goto out;
-      }
+    if(memcmp(buffer1, buffer2, size1) != 0) {
+      /* buffers are different */
+      rc = 0;
+      goto out;
     }
   }
 
-  re = 1;
+  rc = 1;
 
 out:
 
-  if( fd1 > -1) close(fd1);
-  if( fd2 > -1) close(fd2);
+  if(fd1 > -1) close(fd1);
+  if(fd2 > -1) close(fd2);
 
-  c_free_multibyte( wf1 );
-  c_free_multibyte( wf2 );
-  return re;
+  c_free_multibyte(wf1);
+  c_free_multibyte(wf2);
+  return rc;
 
 }
 
diff --git a/tests/std_tests/check_std_c_file.c b/tests/std_tests/check_std_c_file.c
index 165168adbd..44c8be9116 100644
--- a/tests/std_tests/check_std_c_file.c
+++ b/tests/std_tests/check_std_c_file.c
@@ -96,6 +96,19 @@ static void check_c_compare_file(void **state)
   rc = c_compare_file( check_src_file, check_dst_file );
   assert_int_equal(rc, 1);
 
+  /* Check error conditions */
+  rc = c_compare_file( NULL, check_dst_file );
+  assert_int_equal(rc, -1);
+  rc = c_compare_file( check_dst_file, NULL );
+  assert_int_equal(rc, -1);
+  rc = c_compare_file( NULL, NULL );
+  assert_int_equal(rc, -1);
+
+  rc = c_compare_file( check_src_file, "/I_do_not_exist_in_the_filesystem.dummy");
+  assert_int_equal(rc, -1);
+  rc = c_compare_file( "/I_do_not_exist_in_the_filesystem.dummy", check_dst_file);
+  assert_int_equal(rc, -1);
+
   rc = system("echo \"hallo42\" > /tmp/check/foo.txt");
   assert_int_equal(rc, 0);
   rc = system("echo \"hallo52\" > /tmp/check/bar.txt");
@@ -123,8 +136,6 @@ static void check_c_compare_file(void **state)
   rc = c_copy(check_src_file, check_dst_file, 0644);
   assert_int_equal(rc, 0);
 
-  rc = c_compare_file( check_src_file, check_dst_file );
-  assert_int_equal(rc, 1);
 }
 
 int torture_run_tests(void)