diff --git a/src/goto-instrument/unwindset.cpp b/src/goto-instrument/unwindset.cpp
index 982cc51b1da..8c73f15d1cb 100644
--- a/src/goto-instrument/unwindset.cpp
+++ b/src/goto-instrument/unwindset.cpp
@@ -36,7 +36,13 @@ void unwindsett::parse_unwindset_one_loop(
   if(val.empty())
     return;
 
+// Work around spurious GCC 12 warning about thread_nr being uninitialised.
+#pragma GCC diagnostic push
+#ifndef __clang__
+#  pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif
   optionalt<unsigned> thread_nr;
+#pragma GCC diagnostic pop
   if(isdigit(val[0]))
   {
     auto c_pos = val.find(':');
@@ -157,7 +163,13 @@ void unwindsett::parse_unwindset_one_loop(
           return;
         }
         else
+// Work around spurious GCC 12 warning about thread_nr being uninitialised.
+#pragma GCC diagnostic push
+#ifndef __clang__
+#  pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif
           id = function_id + "." + std::to_string(*nr);
+#pragma GCC diagnostic pop
       }
     }
 
diff --git a/src/util/cmdline.cpp b/src/util/cmdline.cpp
index 84530430ae1..fe9ee544680 100644
--- a/src/util/cmdline.cpp
+++ b/src/util/cmdline.cpp
@@ -296,7 +296,13 @@ bool cmdlinet::parse_arguments(int argc, const char **argv)
         return true;
       }
 
+      // Work around spurious GCC 12 warning about optnr being uninitialised.
+#pragma GCC diagnostic push
+#ifndef __clang__
+#  pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif
       options[*optnr].isset = true;
+#pragma GCC diagnostic pop
 
       if(options[*optnr].hasval)
       {
diff --git a/src/util/simplify_expr_int.cpp b/src/util/simplify_expr_int.cpp
index 3d132ca47fa..5096db9a3bf 100644
--- a/src/util/simplify_expr_int.cpp
+++ b/src/util/simplify_expr_int.cpp
@@ -159,6 +159,12 @@ static bool mul_expr(
   return true;
 }
 
+// Work around spurious GCC 12 warning about c_sizeof_type being
+// uninitialised in its destructor (!).
+#pragma GCC diagnostic push
+#ifndef __clang__
+#  pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif
 simplify_exprt::resultt<> simplify_exprt::simplify_mult(const mult_exprt &expr)
 {
   // check to see if it is a number type
@@ -270,6 +276,7 @@ simplify_exprt::resultt<> simplify_exprt::simplify_mult(const mult_exprt &expr)
     return std::move(tmp);
   }
 }
+#pragma GCC diagnostic pop
 
 simplify_exprt::resultt<> simplify_exprt::simplify_div(const div_exprt &expr)
 {