GTK_IM_MODULE=xim breaks dead keys in GTK and QT applications

I'm using XIM to have the compose key take into account my ~/.XCompose file (it's the only input method that takes it into account, all the others I tried use hard-coded tables). However, it is breaking the dead keys in GTK and QT application: If in charmap (GTK) I press ^ a, it just prints a. The ^ key is recognized though, as it makes the caret stop blinking while I'm pressing it. In kate (QT), it prints ^a instead (two separate characters). **How can I make dead keys work when using XIM?** --- Here are the relevant environment variables: $ env | grep '\(IM\|XMODIFIERS\)' ECORE_IMF_MODULE=xim QT_IM_MODULE=xim GTK_IM_MODULE=xim XMODIFIERS=@im=none And here is the output of xev when pressing ^ a: KeyPress event, serial 37, synthetic NO, window 0x1a00001, root 0xd9, subw 0x0, time 29204065, (131,637), root:(135,656), state 0x10, keycode 34 (keysym 0xfe52, dead_circumflex), same_screen YES, XLookupString gives 1 bytes: (5e) "^" XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyRelease event, serial 37, synthetic NO, window 0x1a00001, root 0xd9, subw 0x0, time 29204135, (131,637), root:(135,656), state 0x10, keycode 34 (keysym 0xfe52, dead_circumflex), same_screen YES, XLookupString gives 1 bytes: (5e) "^" XFilterEvent returns: False KeyPress event, serial 37, synthetic NO, window 0x1a00001, root 0xd9, subw 0x0, time 29204545, (131,637), root:(135,656), state 0x10, keycode 24 (keysym 0x61, a), same_screen YES, XLookupString gives 1 bytes: (61) "a" XmbLookupString gives 1 bytes: (61) "a" XFilterEvent returns: False KeyRelease event, serial 37, synthetic NO, window 0x1a00001, root 0xd9, subw 0x0, time 29204614, (131,637), root:(135,656), state 0x10, keycode 24 (keysym 0x61, a), same_screen YES, XLookupString gives 1 bytes: (61) "a" XFilterEvent returns: False