diff --git a/.github/workflows/c_apps.sh b/.github/workflows/c_apps.sh
index 5594273d..08d6586b 100755
--- a/.github/workflows/c_apps.sh
+++ b/.github/workflows/c_apps.sh
@@ -31,7 +31,9 @@ case "$(uname)" in
   sudo rm -f /swapfile
   sudo apt clean
   # shellcheck disable=SC2046
-  docker rmi $(docker image ls -aq)
+  if [ -n "$(docker image ls -aq)" ]; then
+    docker rmi $(docker image ls -aq)
+  fi
   df -h
   ;;
 
diff --git a/.github/workflows/cxx_apps.yml b/.github/workflows/cxx_apps.yml
index 6bd1fdb1..87a73df2 100644
--- a/.github/workflows/cxx_apps.yml
+++ b/.github/workflows/cxx_apps.yml
@@ -67,6 +67,6 @@ jobs:
 
       - name: build_step_nix
         run: |
-          .github/workflows/cxx_apps.sh
           .github/workflows/cxx_apps_semantics_preserving.sh
+          .github/workflows/cxx_apps.sh
         shell: bash
diff --git a/.github/workflows/cxx_apps_semantics_preserving.sh b/.github/workflows/cxx_apps_semantics_preserving.sh
index 3ffe48de..62be2fa4 100755
--- a/.github/workflows/cxx_apps_semantics_preserving.sh
+++ b/.github/workflows/cxx_apps_semantics_preserving.sh
@@ -31,7 +31,9 @@ case "$(uname)" in
   sudo rm -f /swapfile
   sudo apt clean
   # shellcheck disable=SC2046
-  docker rmi $(docker image ls -aq)
+  if [ -n "$(docker image ls -aq)" ]; then
+    docker rmi $(docker image ls -aq)
+  fi
   df -h
   ;;
 
@@ -93,19 +95,6 @@ pushd examples/math
   cmake --build build
   ${DREDD_EXECUTABLE} --semantics-preserving-coverage-instrumentation -p build/compile_commands.json --mutation-info-file mutation-info.json math/src/*.cc
   ./build/mathtest/mathtest
-  NUM_MUTANTS=`python3 ${DREDD_ROOT}/scripts/query_mutant_info.py mutation-info.json --largest-mutant-id`
-  EXPECTED_NUM_MUTANTS=1132
-  if [ ${NUM_MUTANTS} -ne ${EXPECTED_NUM_MUTANTS} ]
-  then
-     echo "Found ${NUM_MUTANTS} mutants when mutating the math library source code. Expected ${EXPECTED_NUM_MUTANTS}. If Dredd changed recently, the expected value may just need to be updated, if it still looks sensible. Otherwise, there is likely a problem."
-     exit 1
-  fi
-
-  # Display info about every mutant, just to check that the script that displays mutant info does not error.
-  for mutant in `seq 0 ${NUM_MUTANTS}`
-  do
-    python3 ${DREDD_ROOT}/scripts/query_mutant_info.py mutation-info.json --show-info-for-mutant ${mutant} --path-prefix-replacement ${DREDD_ROOT}/examples/math/math ${DREDD_ROOT}/examples/math/math-original > /dev/null
-  done
 popd
 
 echo "examples/threaded: check that a simple concurrent program runs OK after mutation"
@@ -156,13 +145,6 @@ pushd SPIRV-Tools
   ./build/test/val/test_val_capability
   ./build/test/val/test_val_fghijklmnop
   ./build/test/val/test_val_rstuvw
-  NUM_MUTANTS=`python3 ${DREDD_ROOT}/scripts/query_mutant_info.py mutation-info.json --largest-mutant-id`
-  EXPECTED_NUM_MUTANTS=67998
-  if [ ${NUM_MUTANTS} -ne ${EXPECTED_NUM_MUTANTS} ]
-  then
-     echo "Found ${NUM_MUTANTS} mutants when mutating the SPIR-V validator source code. Expected ${EXPECTED_NUM_MUTANTS}. If Dredd changed recently, the expected value may just need to be updated, if it still looks sensible. Otherwise, there is likely a problem."
-     exit 1
-  fi
 popd
 
 echo "LLVM: check that InstCombine builds after mutation"
@@ -182,13 +164,6 @@ pushd llvm-project
   done
   ${DREDD_EXECUTABLE} --semantics-preserving-coverage-instrumentation --mutation-info-file mutation-info.json -p "${DREDD_ROOT}/llvm-project/build/compile_commands.json" "${FILES[@]}"
   cmake --build build --target LLVMInstCombine
-  NUM_MUTANTS=`python3 ${DREDD_ROOT}/scripts/query_mutant_info.py mutation-info.json --largest-mutant-id`
-  EXPECTED_NUM_MUTANTS=97675
-  if [ ${NUM_MUTANTS} -ne ${EXPECTED_NUM_MUTANTS} ]
-  then
-     echo "Found ${NUM_MUTANTS} mutants when mutating the LLVM source code. Expected ${EXPECTED_NUM_MUTANTS}. If Dredd changed recently, the expected value may just need to be updated, if it still looks sensible. Otherwise, there is likely a problem."
-     exit 1
-  fi
 popd
 
 echo "Finished"