diff --git a/gnu/local.mk b/gnu/local.mk
index 6308a81e66..8ed01eb2fb 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1,5 +1,5 @@
 # GNU Guix --- Functional package management for GNU
-# Copyright © 2012, 2013, 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
+# Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
 # Copyright © 2013, 2014, 2015, 2016, 2017 Andreas Enge <andreas@enge.fr>
 # Copyright © 2016 Mathieu Lirzin <mthl@gnu.org>
 # Copyright © 2013, 2014, 2015, 2016, 2017 Mark H Weaver <mhw@netris.org>
@@ -959,6 +959,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/policycoreutils-make-sepolicy-use-python3.patch	\
   %D%/packages/patches/portaudio-audacity-compat.patch		\
   %D%/packages/patches/portmidi-modular-build.patch		\
+  %D%/packages/patches/potrace-tests.patch			\
   %D%/packages/patches/procmail-ambiguous-getline-debian.patch  \
   %D%/packages/patches/procmail-CVE-2014-3618.patch		\
   %D%/packages/patches/procmail-CVE-2017-16844.patch		\
diff --git a/gnu/packages/fontutils.scm b/gnu/packages/fontutils.scm
index d6c093cd27..666c68f424 100644
--- a/gnu/packages/fontutils.scm
+++ b/gnu/packages/fontutils.scm
@@ -406,7 +406,8 @@ and returns a sequence of positioned glyphids from the font.")
                           "/potrace-" version ".tar.gz"))
       (sha256
        (base32
-        "17ajildjp14shsy339xarh1lw1p0k60la08ahl638a73mh23kcx9"))))
+        "17ajildjp14shsy339xarh1lw1p0k60la08ahl638a73mh23kcx9"))
+      (patches (search-patches "potrace-tests.patch"))))
     (build-system gnu-build-system)
     (native-inputs `(("ghostscript" ,ghostscript))) ;for tests
     (inputs `(("zlib" ,zlib)))
diff --git a/gnu/packages/patches/potrace-tests.patch b/gnu/packages/patches/potrace-tests.patch
new file mode 100644
index 0000000000..407be98dab
--- /dev/null
+++ b/gnu/packages/patches/potrace-tests.patch
@@ -0,0 +1,50 @@
+This relaxes the comparison threshold between the reference data
+and the bitmaps produced by Ghostscript interpreting the vectorized
+image.  Apparently the threshold has become too low with the switch
+to from Ghostscript 2.21 to 2.22.
+
+--- potrace-1.15/check/postscript-check.sh	2018-01-06 19:47:26.194900686 +0100
++++ potrace-1.15/check/postscript-check.sh	2018-01-06 19:51:35.937503739 +0100
+@@ -70,15 +70,15 @@ if test $? -ne 0; then
+     echo "Something is wrong with $GS; skipping this test" >& 2
+     exit 77
+ fi 
+-actiondiff "$TMP2" "$REFDATA" 1000
++actiondiff "$TMP2" "$REFDATA" 1500
+ 
+ action $POTRACE -r50 -p -L 0 -B 0 --opaque -o "$TMP1" "$DATA"
+ action "$GS" -q -dNOPAUSE -sDEVICE=pbmraw -g460x394 -r100x100 -sOutputFile="$TMP2" -- "$TMP1"
+-actiondiff "$TMP2" "$REFDATA" 1200
++actiondiff "$TMP2" "$REFDATA" 1500
+ 
+ action $POTRACE -r50 -p -L 0 -B 0 -A 160 -o "$TMP1" "$DATA"
+ action "$GS" -q -dNOPAUSE -sDEVICE=pbmraw -g568x528 -r100x100 -sOutputFile="$TMP2" -- "$TMP1"
+-actiondiff "$TMP2" "$REFDATAROT" 1200
++actiondiff "$TMP2" "$REFDATAROT" 1500
+ 
+ action rm -f "$TMP1"
+ action rm -f "$TMP2"
+
+--- potrace-1.15/check/pdf-check.sh	2018-01-06 19:47:28.698886663 +0100
++++ potrace-1.15/check/pdf-check.sh	2018-01-06 20:54:14.895460329 +0100
+@@ -72,15 +72,15 @@ if test $? -ne 0 -o ! -f "$TMP2"; then
+     echo "GS does not understand PDF; skipping this test" >& 2
+     exit 77
+ fi 
+-actiondiff "$TMP2" "$REFDATA" 1000
++actiondiff "$TMP2" "$REFDATA" 1500
+ 
+ action $POTRACE -r50 -p -L 0 -B 0 --opaque -b pdf -o "$TMP1" "$DATA"
+ action "$GS" -q -dNOPAUSE -sDEVICE=pbmraw -g460x394 -r100x100 -sOutputFile="$TMP2" -- "$TMP1"
+-actiondiff "$TMP2" "$REFDATA" 1200
++actiondiff "$TMP2" "$REFDATA" 1500
+ 
+ action $POTRACE -r50 -p -L 0 -B 0 -A 160 -b pdf -o "$TMP1" "$DATA"
+ action "$GS" -q -dNOPAUSE -sDEVICE=pbmraw -g568x528 -r100x100 -sOutputFile="$TMP2" -- "$TMP1"
+-actiondiff "$TMP2" "$REFDATAROT" 1200
++actiondiff "$TMP2" "$REFDATAROT" 1500
+ 
+ action rm -f "$TMP1"
+ action rm -f "$TMP2"
+
+Diff finished.  Sat Jan  6 20:54:50 2018