diff --git a/spec/awscr-signer/signers/v4_spec.cr b/spec/awscr-signer/signers/v4_spec.cr
index 0dc090c..fd4f597 100644
--- a/spec/awscr-signer/signers/v4_spec.cr
+++ b/spec/awscr-signer/signers/v4_spec.cr
@@ -17,7 +17,7 @@ module Awscr
 
               digest = OpenSSL::Digest.new("SHA256")
               digest.update("BODY")
-              request.headers["X-Amz-Content-Sha256"].should eq(digest.hexdigest)
+              request.headers["X-Amz-Content-Sha256"].should eq(digest.final.hexstring)
               request.headers["Authorization"].should eq("AWS4-HMAC-SHA256 Credential=AKIDEXAMPLE/20150101/us-east-1/s3/aws4_request, SignedHeaders=x-amz-content-sha256;x-amz-date, Signature=791f608d3f2173e73123252f6d3eae407fedbe55d8d62d06fc45bd5ea7584fc0")
             end
           end
diff --git a/src/awscr-signer/v4/request.cr b/src/awscr-signer/v4/request.cr
index 49ce3f2..f309f32 100644
--- a/src/awscr-signer/v4/request.cr
+++ b/src/awscr-signer/v4/request.cr
@@ -72,7 +72,7 @@ module Awscr
           end
           body.rewind
 
-          digest.hexdigest
+          digest.final.hexstring
         end
       end
 
diff --git a/src/awscr-signer/v4/signature.cr b/src/awscr-signer/v4/signature.cr
index fab33a7..cbe0731 100644
--- a/src/awscr-signer/v4/signature.cr
+++ b/src/awscr-signer/v4/signature.cr
@@ -52,7 +52,7 @@ module Awscr
       private def digest
         digest = OpenSSL::Digest.new("SHA256")
         digest.update(@string)
-        digest.hexdigest
+        digest.final.hexstring
       end
 
       # :nodoc: