diff --git a/modules/compiler_vm/languages/c11.pm b/modules/compiler_vm/languages/c11.pm
index 566796bc..437a3899 100755
--- a/modules/compiler_vm/languages/c11.pm
+++ b/modules/compiler_vm/languages/c11.pm
@@ -11,7 +11,7 @@ sub initialize {
 
   $self->{sourcefile}      = 'prog.c';
   $self->{execfile}        = 'prog';
-  $self->{default_options} = '-Wextra -Wall -Wno-unused -pedantic -Wfloat-equal -Wshadow -std=c11 -lm -Wfatal-errors -fsanitize=bounds -fsanitize=alignment';
+  $self->{default_options} = '-Wextra -Wall -Wno-unused -pedantic -Wfloat-equal -Wshadow -std=c11 -lm -Wfatal-errors -fsanitize=bounds -fsanitize=alignment -fsanitize=undefined';
   $self->{options_paste}   = '-fdiagnostics-show-caret';
   $self->{options_nopaste} = '-fno-diagnostics-show-caret';
   $self->{cmdline}         = 'gcc -ggdb -g3 $sourcefile $options -o $execfile';
diff --git a/modules/compiler_vm/languages/c89.pm b/modules/compiler_vm/languages/c89.pm
index 8bbb309b..e537331e 100755
--- a/modules/compiler_vm/languages/c89.pm
+++ b/modules/compiler_vm/languages/c89.pm
@@ -11,7 +11,7 @@ sub initialize {
 
   $self->{sourcefile}      = 'prog.c';
   $self->{execfile}        = 'prog';
-  $self->{default_options} = '-Wextra -Wall -Wno-unused -pedantic -Wfloat-equal -Wshadow -std=c89 -lm -Wfatal-errors -fsanitize=bounds -fsanitize=alignment';
+  $self->{default_options} = '-Wextra -Wall -Wno-unused -pedantic -Wfloat-equal -Wshadow -std=c89 -lm -Wfatal-errors -fsanitize=bounds -fsanitize=alignment -fsanitize=undefined';
   $self->{options_paste}   = '-fdiagnostics-show-caret';
   $self->{options_nopaste} = '-fno-diagnostics-show-caret';
   $self->{cmdline}         = 'gcc -ggdb -g3 $sourcefile $options -o $execfile';
diff --git a/modules/compiler_vm/languages/c99.pm b/modules/compiler_vm/languages/c99.pm
index 336852ff..422ac0a7 100755
--- a/modules/compiler_vm/languages/c99.pm
+++ b/modules/compiler_vm/languages/c99.pm
@@ -11,7 +11,7 @@ sub initialize {
 
   $self->{sourcefile}      = 'prog.c';
   $self->{execfile}        = 'prog';
-  $self->{default_options} = '-Wextra -Wall -Wno-unused -pedantic -Wfloat-equal -Wshadow -std=c99 -lm -Wfatal-errors -fsanitize=bounds -fsanitize=alignment';
+  $self->{default_options} = '-Wextra -Wall -Wno-unused -pedantic -Wfloat-equal -Wshadow -std=c99 -lm -Wfatal-errors -fsanitize=bounds -fsanitize=alignment -fsanitize=undefined';
   $self->{options_paste}   = '-fdiagnostics-show-caret';
   $self->{options_nopaste} = '-fno-diagnostics-show-caret';
   $self->{cmdline}         = 'gcc -ggdb -g3 $sourcefile $options -o $execfile';