diff --git a/.appveyor.yml b/.appveyor.yml
index 91d4010..098dfa1 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -50,4 +50,4 @@ build: off
 test_script:
     - conda.exe build recipe -m .ci_support\%CONFIG%.yaml --quiet
 deploy_script:
-    - cmd: upload_package .\ .\recipe .ci_support\%CONFIG%.yaml
+    - cmd: upload_package .\ .\recipe .ci_support\%CONFIG%.yaml
\ No newline at end of file
diff --git a/.ci_support/linux_cxx_compilergxx.yaml b/.ci_support/linux_cxx_compilergxx.yaml
new file mode 100644
index 0000000..f19221a
--- /dev/null
+++ b/.ci_support/linux_cxx_compilergxx.yaml
@@ -0,0 +1,21 @@
+build_number_decrement:
+- '0'
+channel_sources:
+- conda-forge/label/gcc7,defaults
+channel_targets:
+- conda-forge gcc7
+cxx_compiler:
+- gxx
+docker_image:
+- conda/c3i-linux-64
+libxml2:
+- '2.9'
+pin_run_as_build:
+  libxml2:
+    max_pin: x.x
+zip_keys:
+- - cxx_compiler
+  - channel_sources
+  - channel_targets
+  - docker_image
+  - build_number_decrement
diff --git a/.ci_support/linux_.yaml b/.ci_support/linux_cxx_compilertoolchain_cxx.yaml
similarity index 59%
rename from .ci_support/linux_.yaml
rename to .ci_support/linux_cxx_compilertoolchain_cxx.yaml
index 5a4bdcb..46f5344 100644
--- a/.ci_support/linux_.yaml
+++ b/.ci_support/linux_cxx_compilertoolchain_cxx.yaml
@@ -1,3 +1,5 @@
+build_number_decrement:
+- '1000'
 channel_sources:
 - conda-forge,defaults
 channel_targets:
@@ -11,3 +13,9 @@ libxml2:
 pin_run_as_build:
   libxml2:
     max_pin: x.x
+zip_keys:
+- - cxx_compiler
+  - channel_sources
+  - channel_targets
+  - docker_image
+  - build_number_decrement
diff --git a/.ci_support/osx_cxx_compilerclangxx.yaml b/.ci_support/osx_cxx_compilerclangxx.yaml
new file mode 100644
index 0000000..464dd66
--- /dev/null
+++ b/.ci_support/osx_cxx_compilerclangxx.yaml
@@ -0,0 +1,24 @@
+MACOSX_DEPLOYMENT_TARGET:
+- '10.9'
+build_number_decrement:
+- '0'
+channel_sources:
+- conda-forge/label/gcc7,defaults
+channel_targets:
+- conda-forge gcc7
+cxx_compiler:
+- clangxx
+libxml2:
+- '2.9'
+macos_machine:
+- x86_64-apple-darwin13.4.0
+macos_min_version:
+- '10.9'
+pin_run_as_build:
+  libxml2:
+    max_pin: x.x
+zip_keys:
+- - cxx_compiler
+  - channel_sources
+  - channel_targets
+  - build_number_decrement
diff --git a/.ci_support/osx_.yaml b/.ci_support/osx_cxx_compilertoolchain_cxx.yaml
similarity index 68%
rename from .ci_support/osx_.yaml
rename to .ci_support/osx_cxx_compilertoolchain_cxx.yaml
index c2e5870..dc0c453 100644
--- a/.ci_support/osx_.yaml
+++ b/.ci_support/osx_cxx_compilertoolchain_cxx.yaml
@@ -1,5 +1,7 @@
 MACOSX_DEPLOYMENT_TARGET:
 - '10.9'
+build_number_decrement:
+- '1000'
 channel_sources:
 - conda-forge,defaults
 channel_targets:
@@ -15,3 +17,8 @@ macos_min_version:
 pin_run_as_build:
   libxml2:
     max_pin: x.x
+zip_keys:
+- - cxx_compiler
+  - channel_sources
+  - channel_targets
+  - build_number_decrement
diff --git a/.circleci/config.yml b/.circleci/config.yml
index ede1d94..4088ef8 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -1,11 +1,28 @@
 version: 2
 
 jobs:
-  build_linux_:
+  build_linux_cxx_compilergxx:
     working_directory: ~/test
     machine: true
     environment:
-      - CONFIG: "linux_"
+      - CONFIG: "linux_cxx_compilergxx"
+    steps:
+      - checkout
+      - run:
+          name: Fast finish outdated PRs and merge PRs
+          command: |
+            ./.circleci/fast_finish_ci_pr_build.sh
+            ./.circleci/checkout_merge_commit.sh
+      - run:
+          command: docker pull condaforge/linux-anvil
+      - run:
+          # Run, test and (if we have a BINSTAR_TOKEN) upload the distributions.
+          command: ./.circleci/run_docker_build.sh
+  build_linux_cxx_compilertoolchain_cxx:
+    working_directory: ~/test
+    machine: true
+    environment:
+      - CONFIG: "linux_cxx_compilertoolchain_cxx"
     steps:
       - checkout
       - run:
@@ -23,4 +40,5 @@ workflows:
   version: 2
   build_and_test:
     jobs:
-      - build_linux_
+      - build_linux_cxx_compilergxx
+      - build_linux_cxx_compilertoolchain_cxx
diff --git a/.travis.yml b/.travis.yml
index 5451214..7927252 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,7 +8,8 @@ osx_image: xcode6.4
 
 env:
   matrix:
-    - CONFIG=osx_
+    - CONFIG=osx_cxx_compilerclangxx
+    - CONFIG=osx_cxx_compilertoolchain_cxx
 
   global:
     # The BINSTAR_TOKEN secure variable. This is defined canonically in conda-forge.yml.