diff --git a/gate-core/src/main/java/com/netflix/spinnaker/gate/services/AuthenticationService.java b/gate-core/src/main/java/com/netflix/spinnaker/gate/services/AuthenticationService.java
index 14773db1b5..8682cbb4f2 100644
--- a/gate-core/src/main/java/com/netflix/spinnaker/gate/services/AuthenticationService.java
+++ b/gate-core/src/main/java/com/netflix/spinnaker/gate/services/AuthenticationService.java
@@ -20,6 +20,7 @@
 import com.netflix.spinnaker.fiat.shared.FiatPermissionEvaluator;
 import com.netflix.spinnaker.fiat.shared.FiatService;
 import com.netflix.spinnaker.fiat.shared.FiatStatus;
+import com.netflix.spinnaker.kork.retrofit.Retrofit2SyncCall;
 import com.netflix.spinnaker.security.AuthenticatedRequest;
 import io.micrometer.core.annotation.Counted;
 import java.util.Collection;
@@ -59,7 +60,7 @@ public Collection<? extends GrantedAuthority> login(String userid) {
 
     return AuthenticatedRequest.allowAnonymous(
         () -> {
-          getFiatServiceForLogin().loginUser(userid, "");
+          Retrofit2SyncCall.execute(getFiatServiceForLogin().loginUser(userid));
           return resolveAuthorities(userid);
         });
   }
@@ -73,7 +74,7 @@ public Collection<? extends GrantedAuthority> loginWithRoles(
 
     return AuthenticatedRequest.allowAnonymous(
         () -> {
-          getFiatServiceForLogin().loginWithRoles(userid, roles);
+          Retrofit2SyncCall.execute(getFiatServiceForLogin().loginWithRoles(userid, roles));
           return resolveAuthorities(userid);
         });
   }
@@ -84,7 +85,7 @@ public void logout(String userid) {
       return;
     }
 
-    getFiatServiceForLogin().logoutUser(userid);
+    Retrofit2SyncCall.execute(getFiatServiceForLogin().logoutUser(userid));
     permissionEvaluator.invalidatePermission(userid);
   }
 
diff --git a/gate-core/src/main/java/com/netflix/spinnaker/gate/services/PermissionService.java b/gate-core/src/main/java/com/netflix/spinnaker/gate/services/PermissionService.java
index ec9f01b318..f302bfbeed 100644
--- a/gate-core/src/main/java/com/netflix/spinnaker/gate/services/PermissionService.java
+++ b/gate-core/src/main/java/com/netflix/spinnaker/gate/services/PermissionService.java
@@ -29,6 +29,7 @@
 import com.netflix.spinnaker.kork.core.RetrySupport;
 import com.netflix.spinnaker.kork.exceptions.SpinnakerException;
 import com.netflix.spinnaker.kork.exceptions.SystemException;
+import com.netflix.spinnaker.kork.retrofit.Retrofit2SyncCall;
 import com.netflix.spinnaker.kork.retrofit.exceptions.SpinnakerHttpException;
 import com.netflix.spinnaker.kork.retrofit.exceptions.SpinnakerServerException;
 import com.netflix.spinnaker.security.AuthenticatedRequest;
@@ -78,9 +79,7 @@ public void login(final String userId) {
       try {
         AuthenticatedRequest.allowAnonymous(
             () -> {
-              // TODO(jvz): FiatService::loginUser should have only one parameter as Retrofit no
-              // longer requires this body parameter
-              getFiatServiceForLogin().loginUser(userId, "");
+              Retrofit2SyncCall.execute(getFiatServiceForLogin().loginUser(userId));
               permissionEvaluator.invalidatePermission(userId);
               return null;
             });
@@ -95,7 +94,7 @@ public void loginWithRoles(final String userId, final Collection<String> roles)
       try {
         AuthenticatedRequest.allowAnonymous(
             () -> {
-              getFiatServiceForLogin().loginWithRoles(userId, roles);
+              Retrofit2SyncCall.execute(getFiatServiceForLogin().loginWithRoles(userId, roles));
               permissionEvaluator.invalidatePermission(userId);
               return null;
             });
@@ -108,7 +107,7 @@ public void loginWithRoles(final String userId, final Collection<String> roles)
   public void logout(String userId) {
     if (fiatStatus.isEnabled()) {
       try {
-        getFiatServiceForLogin().logoutUser(userId);
+        Retrofit2SyncCall.execute(getFiatServiceForLogin().logoutUser(userId));
         permissionEvaluator.invalidatePermission(userId);
       } catch (SpinnakerServerException e) {
         throw UpstreamBadRequest.classifyError(e);
@@ -119,7 +118,7 @@ public void logout(String userId) {
   public void sync() {
     if (fiatStatus.isEnabled()) {
       try {
-        getFiatServiceForLogin().sync(List.of());
+        Retrofit2SyncCall.execute(getFiatServiceForLogin().sync(List.of()));
       } catch (SpinnakerServerException e) {
         throw UpstreamBadRequest.classifyError(e);
       }