diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
index 4f491a6c12..21028f85be 100644
--- a/.github/workflows/ubuntu.yml
+++ b/.github/workflows/ubuntu.yml
@@ -108,7 +108,7 @@ jobs:
     container: ubuntu:focal
     strategy:
       matrix:
-        target: [ci_cmake_flags, ci_test_diagnostics, ci_test_noexceptions, ci_test_noimplicitconversions, ci_test_legacycomparison, ci_test_noglobaludls]
+        target: [ci_cmake_flags, ci_test_diagnostics, ci_test_diagnostic_positions, ci_test_noexceptions, ci_test_noimplicitconversions, ci_test_legacycomparison, ci_test_noglobaludls]
     steps:
       - name: Install build-essential
         run: apt-get update ; apt-get install -y build-essential unzip wget git
diff --git a/cmake/ci.cmake b/cmake/ci.cmake
index 67b2254e5e..1b163f1e80 100644
--- a/cmake/ci.cmake
+++ b/cmake/ci.cmake
@@ -551,6 +551,20 @@ add_custom_target(ci_test_diagnostics
     COMMENT "Compile and test with improved diagnostics enabled"
 )
 
+###############################################################################
+# Enable diagnostic positions support.
+###############################################################################
+
+add_custom_target(ci_test_diagnostic_positions
+    COMMAND ${CMAKE_COMMAND}
+    -DCMAKE_BUILD_TYPE=Debug -GNinja
+    -DJSON_BuildTests=ON -DJSON_Diagnostic_Positions=ON
+    -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_diagnostic_positions
+    COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_diagnostic_positions
+    COMMAND cd ${PROJECT_BINARY_DIR}/build_diagnostic_positions && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
+    COMMENT "Compile and test with diagnostic positions enabled"
+)
+
 ###############################################################################
 # Enable legacy discarded value comparison.
 ###############################################################################
@@ -910,7 +924,7 @@ endfunction()
 ci_get_cmake(3.1.0 CMAKE_3_1_0_BINARY)
 ci_get_cmake(3.13.0 CMAKE_3_13_0_BINARY)
 
-set(JSON_CMAKE_FLAGS_3_1_0 JSON_Diagnostics JSON_GlobalUDLs JSON_ImplicitConversions JSON_DisableEnumSerialization
+set(JSON_CMAKE_FLAGS_3_1_0 JSON_Diagnostics JSON_Diagnostic_Positions JSON_GlobalUDLs JSON_ImplicitConversions JSON_DisableEnumSerialization
     JSON_LegacyDiscardedValueComparison JSON_Install JSON_MultipleHeaders JSON_SystemInclude JSON_Valgrind)
 set(JSON_CMAKE_FLAGS_3_13_0 JSON_BuildTests)