diff --git a/plugins/s3_auth/aws_auth_v4.cc b/plugins/s3_auth/aws_auth_v4.cc
index d21ae814b45..968cfae2c78 100644
--- a/plugins/s3_auth/aws_auth_v4.cc
+++ b/plugins/s3_auth/aws_auth_v4.cc
@@ -93,6 +93,10 @@ uriEncode(const String &in, bool isObjectName)
     } else if (isObjectName && i == '/') {
       /* Encode the forward slash character, '/', everywhere except in the object key name. */
       result << "/";
+    } else if (i == '+') {
+      /* Only written in the example code, but a plus sign is treated as a space regardless of the position and it must be encoded
+       * as "%20" instead of "%2B" */
+      result << "%20";
     } else {
       /* Letters in the hexadecimal value must be upper-case, for example "%1A". */
       result << "%" << std::uppercase << std::setfill('0') << std::setw(2) << std::hex << static_cast<int>(i);
diff --git a/plugins/s3_auth/unit_tests/test_aws_auth_v4.cc b/plugins/s3_auth/unit_tests/test_aws_auth_v4.cc
index 506fef43878..ca2c6bbff63 100644
--- a/plugins/s3_auth/unit_tests/test_aws_auth_v4.cc
+++ b/plugins/s3_auth/unit_tests/test_aws_auth_v4.cc
@@ -57,7 +57,7 @@ TEST_CASE("uriEncode(): encode reserved chars in a name which is not object name
   String encoded  = uriEncode(in, /* isObjectName */ false);
 
   CHECK(3 * in.length() == encoded.length()); /* size of "%NN" = 3 */
-  CHECK_FALSE(encoded.compare("%20%2F%21%22%23%24%25%26%27%28%29%2A%2B%2C%3A%3B%3C%3D%3E%3F%40%5B%5C%5D%5E%60%7B%7C%7D"));
+  CHECK_FALSE(encoded.compare("%20%2F%21%22%23%24%25%26%27%28%29%2A%20%2C%3A%3B%3C%3D%3E%3F%40%5B%5C%5D%5E%60%7B%7C%7D"));
 }
 
 TEST_CASE("uriEncode(): encode reserved chars in an object name", "[AWS][auth][utility]")
@@ -66,7 +66,7 @@ TEST_CASE("uriEncode(): encode reserved chars in an object name", "[AWS][auth][u
   String encoded  = uriEncode(in, /* isObjectName */ true);
 
   CHECK(3 * in.length() - 2 == encoded.length()); /* size of "%NN" = 3, '/' is not encoded */
-  CHECK_FALSE(encoded.compare("%20/%21%22%23%24%25%26%27%28%29%2A%2B%2C%3A%3B%3C%3D%3E%3F%40%5B%5C%5D%5E%60%7B%7C%7D"));
+  CHECK_FALSE(encoded.compare("%20/%21%22%23%24%25%26%27%28%29%2A%20%2C%3A%3B%3C%3D%3E%3F%40%5B%5C%5D%5E%60%7B%7C%7D"));
 }
 
 TEST_CASE("isUriEncoded(): check an empty input", "[AWS][auth][utility]")