Index: openmsx-21.0+dfsg/build/flavour-unittest.mk
===================================================================
--- openmsx-21.0+dfsg.orig/build/flavour-unittest.mk
+++ openmsx-21.0+dfsg/build/flavour-unittest.mk
@@ -2,7 +2,9 @@
 # Build executable that runs unit tests.
 
 # Debug flags.
-CXXFLAGS+=-O3 -g -DUNITTEST -IContrib/catch2 -fsanitize=address
+CXXFLAGS+=-O3 -g -DUNITTEST -IContrib/catch2 -fsanitize=address \
+    -DDEFAULT_FONT=\"/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf\" \
+    -DDEFAULT_MONO_FONT=\"/usr/share/fonts/truetype/dejavu/DejaVuSansMono.ttf\"
 
 # Strip executable?
 OPENMSX_STRIP:=false
