diff --git a/doc/contributing/Makefile b/doc/contributing/Makefile
index 7c010f98a..14b89193f 100644
--- a/doc/contributing/Makefile
+++ b/doc/contributing/Makefile
@@ -1,5 +1,8 @@
 # Makefile for Sphinx documentation
 #
+EPSTOPDF = epstopdf
+DIA = dia
+CONVERT = convert -density 300
 
 # You can set these variables from the command line.
 SPHINXOPTS    = -W --keep-going
diff --git a/doc/installation/Makefile b/doc/installation/Makefile
index fb92c7e7c..85e3da751 100644
--- a/doc/installation/Makefile
+++ b/doc/installation/Makefile
@@ -1,5 +1,8 @@
 # Makefile for Sphinx documentation
 #
+EPSTOPDF = epstopdf
+DIA = dia
+CONVERT = convert -density 300
 
 # You can set these variables from the command line.
 SPHINXOPTS    = -W --keep-going
diff --git a/doc/manual/Makefile b/doc/manual/Makefile
index b0a413e61..e06c24f2b 100644
--- a/doc/manual/Makefile
+++ b/doc/manual/Makefile
@@ -1,6 +1,6 @@
 EPSTOPDF = epstopdf
 DIA = dia
-CONVERT = convert
+CONVERT = convert -density 300
 
 SRC = ../../src
 # Temporary source directory, for build
diff --git a/doc/models/Makefile b/doc/models/Makefile
index e3a8a2dbe..5b3403568 100644
--- a/doc/models/Makefile
+++ b/doc/models/Makefile
@@ -1,6 +1,6 @@
 EPSTOPDF = epstopdf
 DIA = dia
-CONVERT = convert
+CONVERT = convert -density 300
 
 SRC = ../../src
 # Temporary source directory, for build
diff --git a/doc/tutorial/Makefile b/doc/tutorial/Makefile
index fb92c7e7c..85e3da751 100644
--- a/doc/tutorial/Makefile
+++ b/doc/tutorial/Makefile
@@ -1,5 +1,8 @@
 # Makefile for Sphinx documentation
 #
+EPSTOPDF = epstopdf
+DIA = dia
+CONVERT = convert -density 300
 
 # You can set these variables from the command line.
 SPHINXOPTS    = -W --keep-going
diff --git a/src/antenna/doc/Makefile b/src/antenna/doc/Makefile
index 5de021d3a..cc68d7813 100644
--- a/src/antenna/doc/Makefile
+++ b/src/antenna/doc/Makefile
@@ -1,6 +1,6 @@
 EPSTOPDF = epstopdf
 DIA = dia
-CONVERT = convert
+CONVERT = convert -density 300
 
 SOURCE = source
 FIGURES = $(SOURCE)/figures
diff --git a/src/buildings/doc/Makefile b/src/buildings/doc/Makefile
index 06744f2ce..a1859680b 100644
--- a/src/buildings/doc/Makefile
+++ b/src/buildings/doc/Makefile
@@ -1,6 +1,6 @@
 EPSTOPDF = epstopdf
 DIA = dia
-CONVERT = convert
+CONVERT = convert -density 300
 
 SOURCE = source
 FIGURES = $(SOURCE)/figures