diff --git a/regression/ansi-c/gcc_builtin_constant_p1/main.c b/regression/ansi-c/gcc_builtin_constant_p1/main.c
deleted file mode 100644
index 8ce2e0f55229..000000000000
--- a/regression/ansi-c/gcc_builtin_constant_p1/main.c
+++ /dev/null
@@ -1,28 +0,0 @@
-#include <assert.h>
-
-enum { E1=1 } var;
-
-struct whatnot
-{
-} whatnot_var;
-
-int main()
-{
-  // this is gcc only
-
-  #ifdef __GNUC__
-  assert(__builtin_constant_p("some string"));
-  assert(__builtin_constant_p(1.0f));
-  assert(__builtin_constant_p(E1));
-  assert(!__builtin_constant_p(var));
-  assert(!__builtin_constant_p(main));
-  assert(!__builtin_constant_p(whatnot_var));
-  assert(!__builtin_constant_p(&var));
-  assert(__builtin_constant_p(__builtin_constant_p(var)));
-
-  // side-effects are _not_ evaluated
-  int i=0;
-  assert(!__builtin_constant_p(i++));
-  assert(i==0);
-  #endif
-}
diff --git a/regression/cbmc/gcc_builtin_constant_p1/main.c b/regression/cbmc/gcc_builtin_constant_p1/main.c
new file mode 100644
index 000000000000..a0b6e5b8f737
--- /dev/null
+++ b/regression/cbmc/gcc_builtin_constant_p1/main.c
@@ -0,0 +1,45 @@
+#include <assert.h>
+
+enum
+{
+  E1 = 1
+} var;
+
+struct whatnot
+{
+} whatnot_var;
+
+int main()
+{
+  // this is gcc only
+
+#ifdef __GNUC__
+  assert(__builtin_constant_p("some string"));
+  assert(__builtin_constant_p(1.0f));
+  assert(__builtin_constant_p(E1));
+  assert(!__builtin_constant_p(var));
+  assert(!__builtin_constant_p(main));
+  assert(!__builtin_constant_p(whatnot_var));
+  assert(!__builtin_constant_p(&var));
+  assert(__builtin_constant_p(__builtin_constant_p(var)));
+
+  // The following are not constant expressions in the sense of the C standard
+  // and GCC wouldn't deem them constant expressions either, but they are
+  // subject to GCC's constant folding. See also regression test ansi-c/sizeof6.
+  // Clang's behaviour, however, is somewhat different. See
+  // https://github.com/llvm/llvm-project/issues/55946 for further examples of
+  // where they differ.
+  int j;
+#  ifndef __clang__
+  assert(__builtin_constant_p(j * 0));
+  assert(__builtin_constant_p(j - j));
+  assert(__builtin_constant_p(j ? 0ll : 0ll));
+#  endif
+  assert(__builtin_constant_p(0 ? j : 0ll));
+
+  // side-effects are _not_ evaluated
+  int i = 0;
+  assert(!__builtin_constant_p(i++));
+  assert(i == 0);
+#endif
+}
diff --git a/regression/ansi-c/gcc_builtin_constant_p1/test.desc b/regression/cbmc/gcc_builtin_constant_p1/test.desc
similarity index 63%
rename from regression/ansi-c/gcc_builtin_constant_p1/test.desc
rename to regression/cbmc/gcc_builtin_constant_p1/test.desc
index 307a7ac801ea..659a36aac28c 100644
--- a/regression/ansi-c/gcc_builtin_constant_p1/test.desc
+++ b/regression/cbmc/gcc_builtin_constant_p1/test.desc
@@ -1,6 +1,7 @@
-CORE gcc-only broken-test-c++-front-end
+CORE
 main.c
 
+^VERIFICATION SUCCESSFUL$
 ^EXIT=0$
 ^SIGNAL=0$
 --
diff --git a/src/ansi-c/c_typecheck_expr.cpp b/src/ansi-c/c_typecheck_expr.cpp
index 7e60a27a4009..54ea3f02ec5a 100644
--- a/src/ansi-c/c_typecheck_expr.cpp
+++ b/src/ansi-c/c_typecheck_expr.cpp
@@ -3682,6 +3682,8 @@ exprt c_typecheck_baset::do_special_functions(
     {
       is_constant=true;
     }
+    else if(tmp1.id() == ID_string_constant)
+      is_constant = true;
     else
       is_constant=tmp1.is_constant();