diff --git a/tests/interactive.fish b/tests/interactive.fish
index 22bd62762..87c8717e1 100644
--- a/tests/interactive.fish
+++ b/tests/interactive.fish
@@ -33,7 +33,7 @@ cat interactive.config >> $XDG_CONFIG_HOME/fish/config.fish
 say -o cyan "Testing interactive functionality"
 if not type -q expect
     say red "Tests disabled: `expect` not found"
-    exit 0
+    exit 1
 end
 
 function test_file
diff --git a/tests/locale.in b/tests/locale.in
index d08fd7fde..396a40b43 100644
--- a/tests/locale.in
+++ b/tests/locale.in
@@ -1,25 +1,25 @@
 # Test behavior related to the locale.
 
 # Verify that our UTF-8 locale produces the expected output.
-echo -n A\u00FCA | xxd --plain
+echo -n A\u00FCA | display_bytes
 
 # Verify that exporting a change to the C locale produces the expected output.
 # The output should include the literal byte \xFC rather than the UTF-8 sequence for \u00FC.
 begin
 	set -lx LC_ALL C
-	echo -n B\u00FCB | xxd --plain
+	echo -n B\u00FCB | display_bytes
 end
 
 # Since the previous change was localized to a block it should no
 # longer be in effect and we should be back to a UTF-8 locale.
-echo -n C\u00FCC | xxd --plain
+echo -n C\u00FCC | display_bytes
 
 # Verify that setting a non-exported locale var doesn't affect the behavior.
 # The output should include the UTF-8 sequence for \u00FC rather than that literal byte.
 # Just like the previous test.
 begin
 	set -l LC_ALL C
-	echo -n D\u00FCD | xxd --plain
+	echo -n D\u00FCD | display_bytes
 end
 
 # Verify that fish can pass through non-ASCII characters in the C/POSIX
@@ -38,10 +38,8 @@ end
 # echo output directly to the `xxd` program then via a fish instance. The
 # output should be "58c3bb58" for the first statement and "58c3bc58" for the
 # second.
-echo -n X\u00FBX | \
-  xxd --plain
-echo X\u00FCX | env LC_ALL=C ../test/root/bin/fish -c 'read foo; echo -n $foo' | \
-  xxd --plain
+echo -n X\u00FBX | display_bytes
+echo X\u00FCX | env LC_ALL=C ../test/root/bin/fish -c 'read foo; echo -n $foo' | display_bytes
 
 # The next tests deliberately spawn another fish instance to test inheritence of env vars.
 
@@ -51,11 +49,9 @@ echo X\u00FCX | env LC_ALL=C ../test/root/bin/fish -c 'read foo; echo -n $foo' |
 # few single-byte unicode chars (that are not ASCII) are generally in the
 # ISO 8859-x char sets which are encompassed by the C locale. The output should
 # be "59fc59".
-env LC_ALL=C ../test/root/bin/fish -c 'echo -n Y\u00FCY' | \
-  xxd --plain
+env LC_ALL=C ../test/root/bin/fish -c 'echo -n Y\u00FCY' | display_bytes
 
 # The user can specify a wide unicode character (one requiring more than a
 # single byte). In the C/POSIX locales we substitute a question-mark for the
 # unencodable wide char. The output should be "543f54".
-env LC_ALL=C ../test/root/bin/fish -c 'echo -n T\u01FDT' | \
-  xxd --plain
+env LC_ALL=C ../test/root/bin/fish -c 'echo -n T\u01FDT' | display_bytes
diff --git a/tests/locale.out b/tests/locale.out
index b7c97c156..9aa8faf19 100644
--- a/tests/locale.out
+++ b/tests/locale.out
@@ -1,8 +1,16 @@
-41c3bc41
-42fc42
-43c3bc43
-44c3bc44
-58c3bb58
-58c3bc58
-59fc59
-543f54
+0000000 101 303 274 101
+0000004
+0000000 102 374 102
+0000003
+0000000 103 303 274 103
+0000004
+0000000 104 303 274 104
+0000004
+0000000 130 303 273 130
+0000004
+0000000 130 303 274 130
+0000004
+0000000 131 374 131
+0000003
+0000000 124 077 124
+0000003
diff --git a/tests/printf.in b/tests/printf.in
index 3b92cba41..073bfc582 100644
--- a/tests/printf.in
+++ b/tests/printf.in
@@ -28,11 +28,11 @@ printf 'a\cb'
 echo
 
 # Bogus printf specifier, should produce no stdout
-printf "%5" 10 ^ /dev/null
+printf "%5" 10 ^/dev/null
 
 # Octal escapes produce literal bytes, not characters
 # \376 is 0xFE
-printf '\376' | xxd -p
+printf '\376' | display_bytes
 
 # Verify that floating point conversions and output work correctly with
 # different combinations of locales and floating point strings. See issue
diff --git a/tests/printf.out b/tests/printf.out
index 5349b0fbf..ab25c97d5 100644
--- a/tests/printf.out
+++ b/tests/printf.out
@@ -13,7 +13,8 @@ foobarbaz
 I P Q R
 Test escapes
 a
-fe
+0000000 376
+0000001
 1.230000e+00
 3,450000e+00
 4,560000e+00
diff --git a/tests/test1.in b/tests/test1.in
index 6c3ba956b..49bb2f953 100644
--- a/tests/test1.in
+++ b/tests/test1.in
@@ -126,7 +126,7 @@ echo -e 'abc\cdef' # won't output a newline!
 echo ''
 echo -
 
-echo -ne '\376' | xxd -p
+echo -ne '\376' | display_bytes
 
 echo -e Catch your breath
 
diff --git a/tests/test1.out b/tests/test1.out
index 1b5eeade9..c49e5e0a4 100644
--- a/tests/test1.out
+++ b/tests/test1.out
@@ -37,7 +37,8 @@ abcQdef
 abcQ2def
 abc
 -
-fe
+0000000 376
+0000001
 Catch your breath
 abc!def
 abc!1def
diff --git a/tests/test_functions/display_bytes.fish b/tests/test_functions/display_bytes.fish
new file mode 100644
index 000000000..f0e78250f
--- /dev/null
+++ b/tests/test_functions/display_bytes.fish
@@ -0,0 +1,11 @@
+# This is needed because GNU and BSD implementations of `od` differ in the whitespace they emit.
+# In the past we used the `xxd` command which doesn't suffer from such idiosyncrasies but it isn't
+# available on some systems unless you install the Vim editor. Whereas `od` is pretty much
+# universally available. See issue #3797.
+#
+# We use the lowest common denominator format, `-b`, because it should work in all implementations.
+# I wish we could use the `-t` flag but it isn't available in every OS we're likely to run on.
+#
+function display_bytes
+    od -b | sed -e 's/  */ /g' -e 's/  *$//'
+end