diff --git a/src/main/java/com/commafeed/frontend/model/Entry.java b/src/main/java/com/commafeed/frontend/model/Entry.java
index 4458d77c..91e87325 100644
--- a/src/main/java/com/commafeed/frontend/model/Entry.java
+++ b/src/main/java/com/commafeed/frontend/model/Entry.java
@@ -116,10 +116,10 @@ public class Entry implements Serializable {
 	@ApiModelProperty(value = "entry enclosure mime type, if any")
 	private String enclosureType;
 
-	@ApiModelProperty(value = "entry publication date", required = true)
+	@ApiModelProperty(value = "entry publication date", dataType = "number", required = true)
 	private Date date;
 
-	@ApiModelProperty(value = "entry insertion date in the database", required = true)
+	@ApiModelProperty(value = "entry insertion date in the database", dataType = "number", required = true)
 	private Date insertedDate;
 
 	@ApiModelProperty(value = "feed id", required = true)
diff --git a/src/main/java/com/commafeed/frontend/model/Subscription.java b/src/main/java/com/commafeed/frontend/model/Subscription.java
index e2905978..3cc71f92 100644
--- a/src/main/java/com/commafeed/frontend/model/Subscription.java
+++ b/src/main/java/com/commafeed/frontend/model/Subscription.java
@@ -51,10 +51,13 @@ public class Subscription implements Serializable {
 	@ApiModelProperty(value = "error count", required = true)
 	private int errorCount;
 
-	@ApiModelProperty(value = "last time the feed was refreshed", required = true)
+	@ApiModelProperty(value = "last time the feed was refreshed", dataType = "number", required = true)
 	private Date lastRefresh;
 
-	@ApiModelProperty(value = "next time the feed refresh is planned, null if refresh is already queued", required = true)
+	@ApiModelProperty(
+			value = "next time the feed refresh is planned, null if refresh is already queued",
+			dataType = "number",
+			required = true)
 	private Date nextRefresh;
 
 	@ApiModelProperty(value = "this subscription's feed url", required = true)
@@ -75,7 +78,7 @@ public class Subscription implements Serializable {
 	@ApiModelProperty("position of the subscription's in the list")
 	private Integer position;
 
-	@ApiModelProperty("date of the newest item")
+	@ApiModelProperty(value = "date of the newest item", dataType = "number")
 	private Date newestItemTime;
 
 	@ApiModelProperty(value = "JEXL string evaluated on new entries to mark them as read if they do not match")
diff --git a/src/main/java/com/commafeed/frontend/model/UnreadCount.java b/src/main/java/com/commafeed/frontend/model/UnreadCount.java
index 95e3f280..72e4b73f 100644
--- a/src/main/java/com/commafeed/frontend/model/UnreadCount.java
+++ b/src/main/java/com/commafeed/frontend/model/UnreadCount.java
@@ -18,7 +18,7 @@ public class UnreadCount implements Serializable {
 	@ApiModelProperty
 	private long unreadCount;
 
-	@ApiModelProperty
+	@ApiModelProperty(dataType = "number")
 	private Date newestItemTime;
 
 	public UnreadCount() {
diff --git a/src/main/java/com/commafeed/frontend/model/UserModel.java b/src/main/java/com/commafeed/frontend/model/UserModel.java
index b4bd608b..7eb86257 100644
--- a/src/main/java/com/commafeed/frontend/model/UserModel.java
+++ b/src/main/java/com/commafeed/frontend/model/UserModel.java
@@ -30,10 +30,10 @@ public class UserModel implements Serializable {
 	@ApiModelProperty(value = "account status", required = true)
 	private boolean enabled;
 
-	@ApiModelProperty(value = "account creation date", required = true)
+	@ApiModelProperty(value = "account creation date", dataType = "number", required = true)
 	private Date created;
 
-	@ApiModelProperty(value = "last login date")
+	@ApiModelProperty(value = "last login date", dataType = "number")
 	private Date lastLogin;
 
 	@ApiModelProperty(value = "user is admin", required = true)