How to fix "could not find a base address that matches schema http"... in WCF

I'm trying to deploy a WCF service to my server, hosted in IIS. Naturally it works on my machine :)

But when I deploy it, I get the following error:

This collection already contains an address with scheme http. There can be at most one address per scheme in this collection.

Googling on this, I find that I have to put a serviceHostingEnvironment element into the web.config file:

<serviceHostingEnvironment>
  <baseAddressPrefixFilters>
    <add prefix="http://mywebsiteurl"/>
  </baseAddressPrefixFilters>
</serviceHostingEnvironment>

But once I have done this, I get the following:

Could not find a base address that matches scheme http for the endpoint with binding BasicHttpBinding. Registered base address schemes are [https].

It seems it doesn't know what the base address is, but how do I specify it? Here's the relevant section of my web.config file:

<system.serviceModel>
  <serviceHostingEnvironment>
    <baseAddressPrefixFilters>
      <add prefix="http://mywebsiteurl"/>
    </baseAddressPrefixFilters>
  </serviceHostingEnvironment>

  <behaviors>
    <serviceBehaviors>
      <behavior name="WcfPortalBehavior">
        <serviceMetadata httpGetEnabled="true"/>
        <serviceDebug includeExceptionDetailInFaults="true"/>
      </behavior>
    </serviceBehaviors>
  </behaviors>
  <bindings>
    <basicHttpBinding>
      <binding name="BasicHttpBinding_IWcfPortal"
               maxBufferSize="2147483647" maxReceivedMessageSize="2147483647"
               receiveTimeout="00:10:00" sendTimeout="00:10:00"
               openTimeout="00:10:00" closeTimeout="00:10:00">
        <readerQuotas maxBytesPerRead="2147483647" maxArrayLength="2147483647"
               maxStringContentL