-PNGS = $(foreach I,$(ICONS),$(foreach S,$(SIZES),$(I)-$(S).png))
-MONOPNGS = $(foreach I,$(ICONS),$(foreach S,$(SIZES),$(I)-$(S)-mono.png))
-TRUEPNGS = $(foreach I,$(ICONS),$(foreach S,$(SIZES),$(I)-$(S)-true.png))
+PAMS = $(foreach I,$(ICONS),$(foreach S,$(SIZES),$(I)-$(S).pam))
+MONOPAMS = $(foreach I,$(ICONS),$(foreach S,$(SIZES),$(I)-$(S)-mono.pam))
+TRUEPAMS = $(foreach I,$(ICONS),$(foreach S,$(SIZES),$(I)-$(S)-true.pam))
+
+PNGS = $(patsubst %.pam,%.png,$(PAMS))
+MONOPNGS = $(patsubst %.pam,%.png,$(MONOPAMS))
+TRUEPNGS = $(patsubst %.pam,%.png,$(TRUEPAMS))