diff --git a/.github/workflows/doxygen-check.yaml b/.github/workflows/doxygen-check.yaml
index a64edaaf4228..f7ab42925d54 100644
--- a/.github/workflows/doxygen-check.yaml
+++ b/.github/workflows/doxygen-check.yaml
@@ -8,7 +8,7 @@ jobs:
   check-doxygen:
     # Note that the versions used for this `check-doxygen` job should be kept in
     # sync with the `publish` job.
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
     - uses: actions/checkout@v7
     - name: Fetch dependencies
diff --git a/.github/workflows/publish.yaml b/.github/workflows/publish.yaml
index 0b7d82bf90a5..036eef9451a7 100644
--- a/.github/workflows/publish.yaml
+++ b/.github/workflows/publish.yaml
@@ -6,7 +6,7 @@ jobs:
   publish:
     # Note that the versions used for this `publish` job should be kept in sync
     # with the `check-doxygen` job.
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
       - name: Checkout repository
         uses: actions/checkout@v7
diff --git a/.github/workflows/syntax-checks.yaml b/.github/workflows/syntax-checks.yaml
index fd2ed8f31f60..79874c27a773 100644
--- a/.github/workflows/syntax-checks.yaml
+++ b/.github/workflows/syntax-checks.yaml
@@ -6,7 +6,7 @@ on:
 jobs:
   # This job takes approximately 1 minute
   check-clang-format:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v7
         with:
diff --git a/src/analyses/reaching_definitions.h b/src/analyses/reaching_definitions.h
index faa8c46224ad..cde06cb11b5e 100644
--- a/src/analyses/reaching_definitions.h
+++ b/src/analyses/reaching_definitions.h
@@ -30,9 +30,7 @@ Date: February 2013
 #include "ai.h"
 #include "goto_rw.h"
 
-class value_setst;
-class is_threadedt;
-class dirtyt;
+class dirtyt; // IWYU pragma: keep
 class reaching_definitions_analysist;
 
 /// An instance of this class provides an assignment of unique numeric `ID` to
diff --git a/src/analyses/variable-sensitivity/full_array_abstract_object.h b/src/analyses/variable-sensitivity/full_array_abstract_object.h
index be5444cd01b0..200a8773baad 100644
--- a/src/analyses/variable-sensitivity/full_array_abstract_object.h
+++ b/src/analyses/variable-sensitivity/full_array_abstract_object.h
@@ -18,8 +18,6 @@
 
 #include <iosfwd>
 
-class ai_baset;
-
 class full_array_abstract_objectt : public abstract_aggregate_objectt<
                                       full_array_abstract_objectt,
                                       array_aggregate_typet>
diff --git a/src/analyses/variable-sensitivity/liveness_context.h b/src/analyses/variable-sensitivity/liveness_context.h
index ff32786d6482..5f42bfaf3a5f 100644
--- a/src/analyses/variable-sensitivity/liveness_context.h
+++ b/src/analyses/variable-sensitivity/liveness_context.h
@@ -16,8 +16,8 @@
 #define CPROVER_ANALYSES_VARIABLE_SENSITIVITY_LIVENESS_CONTEXT_H
 
 #include <analyses/variable-sensitivity/write_location_context.h>
+
 #include <iostream>
-#include <stack>
 
 /**
  * General implementation of an abstract_objectt which tracks the
diff --git a/src/analyses/variable-sensitivity/write_location_context.h b/src/analyses/variable-sensitivity/write_location_context.h
index 220284c2263b..420c9da2ebd1 100644
--- a/src/analyses/variable-sensitivity/write_location_context.h
+++ b/src/analyses/variable-sensitivity/write_location_context.h
@@ -17,8 +17,8 @@
 #define CPROVER_ANALYSES_VARIABLE_SENSITIVITY_WRITE_LOCATION_CONTEXT_H
 
 #include <analyses/variable-sensitivity/context_abstract_object.h>
+
 #include <iostream>
-#include <stack>
 
 /**
  * General implementation of an abstract_objectt which tracks the
diff --git a/src/pointer-analysis/goto_program_dereference.h b/src/pointer-analysis/goto_program_dereference.h
index 1818323d0de2..2cad984a33c6 100644
--- a/src/pointer-analysis/goto_program_dereference.h
+++ b/src/pointer-analysis/goto_program_dereference.h
@@ -21,7 +21,6 @@ class goto_modelt;
 class namespacet;
 class optionst;
 class symbol_table_baset;
-class symbolt;
 class value_setst;
 
 /// Wrapper for functions removing dereferences in expressions contained in