diff --git a/NEWS b/NEWS
index 9b5d8e99480..753fa5806cc 100644
--- a/NEWS
+++ b/NEWS
@@ -40,6 +40,10 @@ PHP                                                                        NEWS
 - mysqlnd:
   . Fixed #60594 (mysqlnd exposes 160 lines of stats in phpinfo). (PeeHaa)
 
+- OpCache:
+  . Fixed bug #78654 (Incorrectly computed opcache checksum on files with 
+    non-ascii characters). (mhagstrand)
+
 - PCRE:
   . Don't ignore invalid escape sequences. (sjon)
 
diff --git a/ext/opcache/zend_accelerator_util_funcs.c b/ext/opcache/zend_accelerator_util_funcs.c
index be927f64479..71e98a6bdc8 100644
--- a/ext/opcache/zend_accelerator_util_funcs.c
+++ b/ext/opcache/zend_accelerator_util_funcs.c
@@ -834,11 +834,11 @@ zend_op_array* zend_accel_load_script(zend_persistent_script *persistent_script,
 #define ADLER32_DO8(buf, i)     ADLER32_DO4(buf, i); ADLER32_DO4(buf, i + 4);
 #define ADLER32_DO16(buf)       ADLER32_DO8(buf, 0); ADLER32_DO8(buf, 8);
 
-unsigned int zend_adler32(unsigned int checksum, signed char *buf, uint32_t len)
+unsigned int zend_adler32(unsigned int checksum, unsigned char *buf, uint32_t len)
 {
 	unsigned int s1 = checksum & 0xffff;
 	unsigned int s2 = (checksum >> 16) & 0xffff;
-	signed char *end;
+	unsigned char *end;
 
 	while (len >= ADLER32_NMAX) {
 		len -= ADLER32_NMAX;
@@ -876,15 +876,15 @@ unsigned int zend_adler32(unsigned int checksum, signed char *buf, uint32_t len)
 
 unsigned int zend_accel_script_checksum(zend_persistent_script *persistent_script)
 {
-	signed char *mem = (signed char*)persistent_script->mem;
+	unsigned char *mem = (unsigned char*)persistent_script->mem;
 	size_t size = persistent_script->size;
 	size_t persistent_script_check_block_size = ((char *)&(persistent_script->dynamic_members)) - (char *)persistent_script;
 	unsigned int checksum = ADLER32_INIT;
 
-	if (mem < (signed char*)persistent_script) {
-		checksum = zend_adler32(checksum, mem, (signed char*)persistent_script - mem);
-		size -= (signed char*)persistent_script - mem;
-		mem  += (signed char*)persistent_script - mem;
+	if (mem < (unsigned char*)persistent_script) {
+		checksum = zend_adler32(checksum, mem, (unsigned char*)persistent_script - mem);
+		size -= (unsigned char*)persistent_script - mem;
+		mem  += (unsigned char*)persistent_script - mem;
 	}
 
 	zend_adler32(checksum, mem, persistent_script_check_block_size);
diff --git a/ext/opcache/zend_accelerator_util_funcs.h b/ext/opcache/zend_accelerator_util_funcs.h
index 30531fc2e7f..331be541cc6 100644
--- a/ext/opcache/zend_accelerator_util_funcs.h
+++ b/ext/opcache/zend_accelerator_util_funcs.h
@@ -35,7 +35,7 @@ zend_op_array* zend_accel_load_script(zend_persistent_script *persistent_script,
 
 #define ADLER32_INIT 1     /* initial Adler-32 value */
 
-unsigned int zend_adler32(unsigned int checksum, signed char *buf, uint32_t len);
+unsigned int zend_adler32(unsigned int checksum, unsigned char *buf, uint32_t len);
 
 unsigned int zend_accel_script_checksum(zend_persistent_script *persistent_script);
 
diff --git a/ext/opcache/zend_file_cache.c b/ext/opcache/zend_file_cache.c
index 663f511bc17..697bb10b0d7 100644
--- a/ext/opcache/zend_file_cache.c
+++ b/ext/opcache/zend_file_cache.c
@@ -936,7 +936,7 @@ int zend_file_cache_script_store(zend_persistent_script *script, int in_shm)
 	zend_shared_alloc_destroy_xlat_table();
 
 	info.checksum = zend_adler32(ADLER32_INIT, buf, script->size);
-	info.checksum = zend_adler32(info.checksum, (signed char*)ZSTR_VAL((zend_string*)ZCG(mem)), info.str_size);
+	info.checksum = zend_adler32(info.checksum, (unsigned char*)ZSTR_VAL((zend_string*)ZCG(mem)), info.str_size);
 
 #if __has_feature(memory_sanitizer)
 	/* The buffer may contain uninitialized regions. However, the uninitialized parts will not be
@@ -1511,6 +1511,7 @@ zend_persistent_script *zend_file_cache_script_load(zend_file_handle *file_handl
 	zend_accel_hash_entry *bucket;
 	void *mem, *checkpoint, *buf;
 	int cache_it = 1;
+	unsigned int actual_checksum;
 	int ok;
 
 	if (!full_path) {
@@ -1594,8 +1595,8 @@ zend_persistent_script *zend_file_cache_script_load(zend_file_handle *file_handl
 
 	/* verify checksum */
 	if (ZCG(accel_directives).file_cache_consistency_checks &&
-	    zend_adler32(ADLER32_INIT, mem, info.mem_size + info.str_size) != info.checksum) {
-		zend_accel_error(ACCEL_LOG_WARNING, "corrupted file '%s'\n", filename);
+	    (actual_checksum = zend_adler32(ADLER32_INIT, mem, info.mem_size + info.str_size)) != info.checksum) {
+		zend_accel_error(ACCEL_LOG_WARNING, "corrupted file '%s' excepted checksum: 0x%08x actual checksum: 0x%08x\n", filename, info.checksum, actual_checksum);
 		zend_file_cache_unlink(filename);
 		zend_arena_release(&CG(arena), checkpoint);
 		efree(filename);
@@ -1683,6 +1684,8 @@ use_process_mem:
 		zend_accel_hash_update(&ZCSG(hash), ZSTR_VAL(script->script.filename), ZSTR_LEN(script->script.filename), 0, script);
 
 		zend_shared_alloc_unlock();
+		zend_accel_error(ACCEL_LOG_INFO, "File cached script loaded into memory '%s'", ZSTR_VAL(script->script.filename));
+
 		zend_arena_release(&CG(arena), checkpoint);
 	}
 	efree(filename);