diff --git a/docs/images/Makefile b/docs/images/Makefile
--- a/docs/images/Makefile
+++ b/docs/images/Makefile
@@ -1,12 +1,8 @@
 PUMLs = $(wildcard *.puml)
-PDFs = $(patsubst %.puml,%.pdf,$(PUMLs))
 PNGs = $(patsubst %.puml,%.png,$(PUMLs))
 SVGs = $(patsubst %.puml,%.svg,$(PUMLs))
 
-all: $(PNGs) $(PDFs) $(SVGs)
-
-%.pdf: %.puml
-	plantuml -Tpdf $<
+all: $(PNGs) $(SVGs)
 
 %.png: %.puml
 	plantuml -Tpng $<
@@ -14,8 +10,7 @@
 %.svg: %.puml
 	plantuml -Tsvg $<
 
-
 .PHONY: clean
 
 clean:
-	rm -f $(PDFs) $(PNGs) $(SVGs)
+	rm -f $(PNGs) $(SVGs)