diff --git a/regression/goto-instrument/generate-function-body-assert-false-assume-false/test.desc b/regression/goto-instrument/generate-function-body-assert-false-assume-false/test.desc
index 1e241b84ba3..1f3a87f4892 100644
--- a/regression/goto-instrument/generate-function-body-assert-false-assume-false/test.desc
+++ b/regression/goto-instrument/generate-function-body-assert-false-assume-false/test.desc
@@ -5,4 +5,4 @@ main.c
 ^SIGNAL=0$
 ^VERIFICATION FAILED$
 ^\[main.assertion.1\] .* assertion 0: SUCCESS$
-^\[crashes_program.assertion.1\] .* assertion false: FAILURE$
+^\[crashes_program.assertion.1\] .* undefined function should be unreachable: FAILURE$
diff --git a/regression/goto-instrument/generate-function-body-assert-false/test.desc b/regression/goto-instrument/generate-function-body-assert-false/test.desc
index ffc806674b2..e2bee949380 100644
--- a/regression/goto-instrument/generate-function-body-assert-false/test.desc
+++ b/regression/goto-instrument/generate-function-body-assert-false/test.desc
@@ -3,6 +3,6 @@ main.c
 --generate-function-body do_not_call_this --generate-function-body-options assert-false
 ^EXIT=10$
 ^SIGNAL=0$
-^\[do_not_call_this.assertion.1\] .* assertion false: FAILURE$
+^\[do_not_call_this.assertion.1\] .* undefined function should be unreachable: FAILURE$
 --
 ^warning: ignoring
diff --git a/regression/goto-instrument/generate-function-body/test.desc b/regression/goto-instrument/generate-function-body/test.desc
index f9e0afbfd79..bbbf07d8331 100644
--- a/regression/goto-instrument/generate-function-body/test.desc
+++ b/regression/goto-instrument/generate-function-body/test.desc
@@ -5,4 +5,4 @@ main.c
 ^SIGNAL=0$
 ^VERIFICATION FAILED$
 ^\[main.assertion.1\] .* assertion does_not_get_reached: SUCCESS$
-^\[should_be_generated.assertion.1\] .* assertion false: FAILURE$
+^\[should_be_generated.assertion.1\] .* undefined function should be unreachable: FAILURE$
diff --git a/src/goto-instrument/generate_function_bodies.cpp b/src/goto-instrument/generate_function_bodies.cpp
index c190795eaee..0e05b3c4156 100644
--- a/src/goto-instrument/generate_function_bodies.cpp
+++ b/src/goto-instrument/generate_function_bodies.cpp
@@ -105,12 +105,8 @@ class assert_false_generate_function_bodiest : public generate_function_bodiest
     };
     auto assert_instruction =
       add_instruction(goto_programt::make_assertion(false_exprt()));
-    const namespacet ns(symbol_table);
-    std::ostringstream comment_stream;
-    comment_stream << id2string(ID_assertion) << " "
-                   << format(assert_instruction->condition());
     assert_instruction->source_location_nonconst().set_comment(
-      comment_stream.str());
+      "undefined function should be unreachable");
     assert_instruction->source_location_nonconst().set_property_class(
       ID_assertion);
     add_instruction(goto_programt::make_end_function());
@@ -136,12 +132,8 @@ class assert_false_then_assume_false_generate_function_bodiest
     };
     auto assert_instruction =
       add_instruction(goto_programt::make_assertion(false_exprt()));
-    const namespacet ns(symbol_table);
-    std::ostringstream comment_stream;
-    comment_stream << id2string(ID_assertion) << " "
-                   << format(assert_instruction->condition());
     assert_instruction->source_location_nonconst().set_comment(
-      comment_stream.str());
+      "undefined function should be unreachable");
     assert_instruction->source_location_nonconst().set_property_class(
       ID_assertion);
     add_instruction(goto_programt::make_assumption(false_exprt()));