diff --git a/.github/workflows/Linux_versions.yml b/.github/workflows/Linux_versions.yml
index e23c875c..ee5e3a04 100644
--- a/.github/workflows/Linux_versions.yml
+++ b/.github/workflows/Linux_versions.yml
@@ -29,6 +29,7 @@ jobs:
         jasper-version: [2.0.33, 4.0.0]
         bacio-version: [2.4.1, 2.6.0]
         w3emc-version: [2.9.2, 2.10.0]
+        ip-version: [develop, v5.0.0]
         g2c-version: [develop, v2.0.0]
         build-utils: [ON, OFF]
         exclude:
@@ -64,7 +65,7 @@ jobs:
         g2c-cmake-args: -DENABLE_SHARED=ON
         w3emc-version: v${{ matrix.w3emc-version }}
         w3emc-cmake-args: -DBUILD_WITH_BUFR=OFF
-        ip-version: develop
+        ip-version: ${{ matrix.ip-version }}
         key-suffix: -gcc${{ matrix.gcc-version }}
 
     - name: checkout
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8b47843c..f7593b28 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -89,6 +89,11 @@ if (BUILD_WITH_W3EMC)
   endif()
 endif()
 
+# We need g2c if G2C_COMPARE is chosen.
+if (G2C_COMPARE)
+  find_package(g2c 1.7.0 REQUIRED)
+endif()
+
 # Figure whether user wants a _4, a _d, or both libraries.
 if(BUILD_4 AND BUILD_D)
   set(kinds "4" "d")