diff --git a/moto/s3/responses.py b/moto/s3/responses.py
index 89719773..603571c0 100644
--- a/moto/s3/responses.py
+++ b/moto/s3/responses.py
@@ -1081,7 +1081,7 @@ class ResponseObject(_TemplateEnvironmentMixin, ActionAuthenticatorMixin):
                     return 403, {}, ""
             elif signed_url:
                 # coming in from requests.get(s3.generate_presigned_url())
-                if self._invalid_headers(request.url, dict(headers)):
+                if self._invalid_headers(request.url, dict(request.headers)):
                     return 403, {}, S3_INVALID_PRESIGNED_PARAMETERS
 
         if hasattr(request, "body"):
diff --git a/moto/s3/utils.py b/moto/s3/utils.py
index 1ca31ce1..2cdb7e86 100644
--- a/moto/s3/utils.py
+++ b/moto/s3/utils.py
@@ -6,6 +6,7 @@ from boto.s3.key import Key
 import re
 import six
 from six.moves.urllib.parse import urlparse, unquote, quote
+from requests.structures import CaseInsensitiveDict
 import sys
 
 
@@ -62,7 +63,7 @@ def parse_region_from_url(url):
 
 
 def metadata_from_headers(headers):
-    metadata = {}
+    metadata = CaseInsensitiveDict()
     meta_regex = re.compile(r"^x-amz-meta-([a-zA-Z0-9\-_]+)$", flags=re.IGNORECASE)
     for header, value in headers.items():
         if isinstance(header, six.string_types):
diff --git a/tests/test_s3/test_s3.py b/tests/test_s3/test_s3.py
index 4c32e387..57f74543 100644
--- a/tests/test_s3/test_s3.py
+++ b/tests/test_s3/test_s3.py
@@ -4612,6 +4612,7 @@ def test_presigned_url_restrict_parameters():
 def test_presigned_put_url_with_approved_headers():
     bucket = str(uuid.uuid4())
     key = "file.txt"
+    content = b"filecontent"
     expected_contenttype = "app/sth"
     conn = boto3.resource("s3", region_name="us-east-1")
     conn.create_bucket(Bucket=bucket)
@@ -4624,26 +4625,26 @@ def test_presigned_put_url_with_approved_headers():
     )
 
     # Verify S3 throws an error when the header is not provided
-    response = requests.put(url, data="filecontent")
+    response = requests.put(url, data=content)
     response.status_code.should.equal(403)
-    response.content.should.contain("<Code>SignatureDoesNotMatch</Code>")
-    response.content.should.contain(
+    str(response.content).should.contain("<Code>SignatureDoesNotMatch</Code>")
+    str(response.content).should.contain(
         "<Message>The request signature we calculated does not match the signature you provided. Check your key and signing method.</Message>"
     )
 
     # Verify S3 throws an error when the header has the wrong value
     response = requests.put(
-        url, data="filecontent", headers={"Content-Type": "application/unknown"}
+        url, data=content, headers={"Content-Type": "application/unknown"}
     )
     response.status_code.should.equal(403)
-    response.content.should.contain("<Code>SignatureDoesNotMatch</Code>")
-    response.content.should.contain(
+    str(response.content).should.contain("<Code>SignatureDoesNotMatch</Code>")
+    str(response.content).should.contain(
         "<Message>The request signature we calculated does not match the signature you provided. Check your key and signing method.</Message>"
     )
 
     # Verify S3 uploads correctly when providing the meta data
     response = requests.put(
-        url, data="filecontent", headers={"Content-Type": expected_contenttype}
+        url, data=content, headers={"Content-Type": expected_contenttype}
     )
     response.status_code.should.equal(200)
 
@@ -4651,7 +4652,7 @@ def test_presigned_put_url_with_approved_headers():
     obj = s3.get_object(Bucket=bucket, Key=key)
     obj["ContentType"].should.equal(expected_contenttype)
     obj["ContentLength"].should.equal(11)
-    obj["Body"].read().should.equal("filecontent")
+    obj["Body"].read().should.equal(content)
     obj["Metadata"].should.equal({})
 
     s3.delete_object(Bucket=bucket, Key=key)
@@ -4662,6 +4663,7 @@ def test_presigned_put_url_with_approved_headers():
 def test_presigned_put_url_with_custom_headers():
     bucket = str(uuid.uuid4())
     key = "file.txt"
+    content = b"filecontent"
     conn = boto3.resource("s3", region_name="us-east-1")
     conn.create_bucket(Bucket=bucket)
     s3 = boto3.client("s3", region_name="us-east-1")
@@ -4673,13 +4675,13 @@ def test_presigned_put_url_with_custom_headers():
     )
 
     # Verify S3 uploads correctly when providing the meta data
-    response = requests.put(url, data="filecontent")
+    response = requests.put(url, data=content)
     response.status_code.should.equal(200)
 
     # Assert the object exists
     obj = s3.get_object(Bucket=bucket, Key=key)
     obj["ContentLength"].should.equal(11)
-    obj["Body"].read().should.equal("filecontent")
+    obj["Body"].read().should.equal(content)
     obj["Metadata"].should.equal({"venue": "123"})
 
     s3.delete_object(Bucket=bucket, Key=key)