diff --git a/moto/s3/responses.py b/moto/s3/responses.py
index 6abb4f2d1..1cd505cc8 100755
--- a/moto/s3/responses.py
+++ b/moto/s3/responses.py
@@ -4,7 +4,7 @@ import re
 
 import six
 from moto.core.utils import str_to_rfc_1123_datetime
-from six.moves.urllib.parse import parse_qs, urlparse
+from six.moves.urllib.parse import parse_qs, urlparse, unquote
 
 import xmltodict
 
@@ -631,7 +631,7 @@ class ResponseObject(_TemplateEnvironmentMixin):
             upload_id = query['uploadId'][0]
             part_number = int(query['partNumber'][0])
             if 'x-amz-copy-source' in request.headers:
-                src = request.headers.get("x-amz-copy-source").lstrip("/")
+                src = unquote(request.headers.get("x-amz-copy-source")).lstrip("/")
                 src_bucket, src_key = src.split("/", 1)
                 src_range = request.headers.get(
                     'x-amz-copy-source-range', '').split("bytes=")[-1]
@@ -673,7 +673,7 @@ class ResponseObject(_TemplateEnvironmentMixin):
 
         if 'x-amz-copy-source' in request.headers:
             # Copy key
-            src_key_parsed = urlparse(request.headers.get("x-amz-copy-source"))
+            src_key_parsed = urlparse(unquote(request.headers.get("x-amz-copy-source")))
             src_bucket, src_key = src_key_parsed.path.lstrip("/").split("/", 1)
             src_version_id = parse_qs(src_key_parsed.query).get(
                 'versionId', [None])[0]