diff --git a/apis/sts/src/main/java/org/jclouds/aws/filters/FormSignerV4.java b/apis/sts/src/main/java/org/jclouds/aws/filters/FormSignerV4.java
index 2743c3d62e..a1359bbfbc 100644
--- a/apis/sts/src/main/java/org/jclouds/aws/filters/FormSignerV4.java
+++ b/apis/sts/src/main/java/org/jclouds/aws/filters/FormSignerV4.java
@@ -23,9 +23,9 @@ import static com.google.common.hash.Hashing.sha256;
 import static com.google.common.io.BaseEncoding.base16;
 import static com.google.common.net.HttpHeaders.AUTHORIZATION;
 import static com.google.common.net.HttpHeaders.HOST;
-import static javax.ws.rs.core.MediaType.APPLICATION_FORM_URLENCODED;
 import static org.jclouds.aws.reference.FormParameters.ACTION;
 import static org.jclouds.aws.reference.FormParameters.VERSION;
+import static org.jclouds.http.utils.Queries.queryParser;
 
 import java.net.URI;
 import java.security.GeneralSecurityException;
@@ -41,8 +41,6 @@ import org.jclouds.date.TimeStamp;
 import org.jclouds.domain.Credentials;
 import org.jclouds.http.HttpException;
 import org.jclouds.http.HttpRequest;
-import org.jclouds.io.Payload;
-import org.jclouds.io.Payloads;
 import org.jclouds.location.Provider;
 import org.jclouds.providers.ProviderMetadata;
 import org.jclouds.rest.annotations.ApiVersion;
@@ -51,6 +49,7 @@ import com.google.common.base.Joiner;
 import com.google.common.base.Splitter;
 import com.google.common.base.Supplier;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Multimap;
 import com.google.inject.ImplementedBy;
 
 public final class FormSignerV4 implements FormSigner {
@@ -106,7 +105,8 @@ public final class FormSignerV4 implements FormSigner {
       checkArgument(request.getHeaders().containsKey(HOST), "request is not ready to sign; host not present");
       String host = request.getFirstHeaderOrNull(HOST);
       String form = request.getPayload().getRawContent().toString();
-      checkArgument(form.indexOf(ACTION) != -1, "request is not ready to sign; Action not present %s", form);
+      Multimap<String, String> decodedParams = queryParser().apply(form);
+      checkArgument(decodedParams.containsKey(ACTION), "request is not ready to sign; Action not present %s", form);
 
       String timestamp = iso8601Timestamp.get();
       String datestamp = timestamp.substring(0, 8);
@@ -125,8 +125,8 @@ public final class FormSignerV4 implements FormSigner {
             .removeHeader(AUTHORIZATION) //
             .replaceHeader("X-Amz-Date", timestamp);
 
-      if (form.indexOf(VERSION) == -1) {
-         requestBuilder.addFormParam("Version", apiVersion);
+      if (!decodedParams.containsKey(VERSION)) {
+         requestBuilder.addFormParam(VERSION, apiVersion);
       }
 
       Credentials credentials = creds.get();
@@ -151,17 +151,6 @@ public final class FormSignerV4 implements FormSigner {
       return requestBuilder.addHeader(AUTHORIZATION, authorization.toString()).build();
    }
 
-   // TODO: change EC2 apis to add this themselves with @FormParams
-   private Payload addVersionIfNecessary(Payload payload, String form) {
-      if (form.indexOf(VERSION) == -1) {
-         form += "&Version=" + apiVersion;
-         payload = Payloads.newStringPayload(form);
-         payload.getContentMetadata().setContentType(APPLICATION_FORM_URLENCODED);
-         payload.getContentMetadata().setContentLength((long) form.length());
-      }
-      return payload;
-   }
-
    static byte[] signatureKey(String secretKey, String datestamp, String region, String service) {
       byte[] kSecret = ("AWS4" + secretKey).getBytes(UTF_8);
       byte[] kDate = hmacSHA256(datestamp, kSecret);
diff --git a/apis/sts/src/test/java/org/jclouds/aws/filters/FormSignerV4Test.java b/apis/sts/src/test/java/org/jclouds/aws/filters/FormSignerV4Test.java
index 2f94c26b7f..94a8ff6068 100644
--- a/apis/sts/src/test/java/org/jclouds/aws/filters/FormSignerV4Test.java
+++ b/apis/sts/src/test/java/org/jclouds/aws/filters/FormSignerV4Test.java
@@ -80,6 +80,25 @@ public class FormSignerV4Test {
       assertThat(filtered.getFirstHeaderOrNull("Authorization")).endsWith("Signature=" + sampleSignature);
    }
 
+   public void versionSampleRequest() {
+      HttpRequest request = HttpRequest.builder() //
+            .method("POST") //
+            .endpoint("https://iam.amazonaws.com/") //
+            .addHeader("Host", "iam.amazonaws.com") //
+            .payload("Action=CoolVersionWordAction")
+            .build();
+
+      request.getPayload().getContentMetadata().setContentType("application/x-www-form-urlencoded; charset=utf-8");
+
+      FormSignerV4 filter = new FormSignerV4(apiVersion, accessAndSecretKey, timestamp, serviceAndRegion);
+
+      HttpRequest filtered = filter.filter(request);
+
+      assertEquals(filtered.getFirstHeaderOrNull("X-Amz-Date"), timestamp.get());
+
+      assertThat(filtered.getPayload().getRawContent().toString().contains("&Version=2010-05-08"));
+   }
+
    public void sessionTokenRequest() {
       HttpRequest request = HttpRequest.builder() //
             .method("POST") //