diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index a0bc485d..822c665b 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -54,7 +54,7 @@ jobs:
           CC: ${{matrix.cc}}
         run: cmake .
       - run: cmake --build .
-      - run: ctest
+      - run: ctest --output-on-failure
 
   valgrind:
     runs-on: ubuntu-latest
@@ -63,4 +63,4 @@ jobs:
       - run: sudo apt update && sudo apt install valgrind
       - run: cmake -DJANSSON_TEST_WITH_VALGRIND=ON .
       - run: cmake --build .
-      - run: ctest
\ No newline at end of file
+      - run: ctest --output-on-failure
diff --git a/CHANGES b/CHANGES
index c5853c7e..cf3e4ef5 100644
--- a/CHANGES
+++ b/CHANGES
@@ -9,6 +9,10 @@ Work in progress
     is used to switch locales inside the threads (#674, #675, #677. Thanks to
     Bruno Haible the report and help with fixing.)
 
+* Build:
+
+  - Make test output nicer in CMake based builds (#683)
+
 Version 2.14
 ============
 
diff --git a/scripts/clang-format b/scripts/clang-format
index d46056c9..65cb7a69 100755
--- a/scripts/clang-format
+++ b/scripts/clang-format
@@ -1,3 +1,3 @@
 #!/bin/bash
 
-find . -type f -a '(' -name '*.c' -o -name '*.h' ')' | xargs clang-format -i
+git ls-files | grep '\.[ch]$' | xargs clang-format -i
diff --git a/scripts/clang-format-check b/scripts/clang-format-check
index 983e55d9..a75e6b72 100755
--- a/scripts/clang-format-check
+++ b/scripts/clang-format-check
@@ -12,13 +12,16 @@ fi
 errors=0
 paths=$(git ls-files | grep '\.[ch]$')
 for path in $paths; do
+    echo "Checking $path"
+    $CLANG_FORMAT $path > $path.formatted
     in=$(cat $path)
-    out=$($CLANG_FORMAT $path)
+    out=$(cat $path.formatted)
 
     if [ "$in" != "$out" ]; then
-        diff -u -L $path -L "$path.formatted" $path - <<<$out
+        diff -u $path $path.formatted
         errors=1
     fi
+    rm $path.formatted
 done
 
 if [ $errors -ne 0 ]; then
diff --git a/test/.gitignore b/test/.gitignore
index 6a33dea3..93cc8da4 100644
--- a/test/.gitignore
+++ b/test/.gitignore
@@ -7,6 +7,7 @@ suites/api/test_cpp
 suites/api/test_dump
 suites/api/test_dump_callback
 suites/api/test_equal
+suites/api/test_fixed_size
 suites/api/test_load
 suites/api/test_load_callback
 suites/api/test_loadb
diff --git a/test/bin/json_process.c b/test/bin/json_process.c
index fc98543f..3fa926b9 100644
--- a/test/bin/json_process.c
+++ b/test/bin/json_process.c
@@ -35,7 +35,6 @@ struct config {
     int ensure_ascii;
     int sort_keys;
     int strip;
-    int use_env;
     int have_hashseed;
     int hashseed;
     int precision;
@@ -138,10 +137,16 @@ static int cmpfile(const char *str, const char *path, const char *fname) {
     }
 
     buffer = loadfile(file);
-    if (strcmp(buffer, str) != 0)
+    if (strcmp(buffer, str) != 0) {
+        fprintf(stderr, "=== Expected %s ===\n", fname);
+        fprintf(stderr, "%s\n", buffer);
+        fprintf(stderr, "=== Actual %s ===\n", fname);
+        fprintf(stderr, "%s\n", str);
         ret = 1;
-    else
+    } else {
         ret = 0;
+    }
+
     free(buffer);
     fclose(file);
 
@@ -206,8 +211,9 @@ int use_conf(char *test_path) {
         buffer = loadfile(infile);
         json = json_loads(strip(buffer), 0, &error);
         free(buffer);
-    } else
+    } else {
         json = json_loadf(infile, 0, &error);
+    }
 
     fclose(infile);
 
@@ -227,108 +233,6 @@ int use_conf(char *test_path) {
     return ret;
 }
 
-static int getenv_int(const char *name) {
-    char *value, *end;
-    long result;
-
-    value = getenv(name);
-    if (!value)
-        return 0;
-
-    result = strtol(value, &end, 10);
-    if (*end != '\0')
-        return 0;
-
-    return (int)result;
-}
-
-int use_env() {
-    int indent, precision;
-    size_t flags = 0;
-    json_t *json;
-    json_error_t error;
-
-#ifdef _WIN32
-    /* On Windows, set stdout and stderr to binary mode to avoid
-       outputting DOS line terminators */
-    _setmode(_fileno(stdout), _O_BINARY);
-    _setmode(_fileno(stderr), _O_BINARY);
-#endif
-
-    indent = getenv_int("JSON_INDENT");
-    if (indent < 0 || indent > 31) {
-        fprintf(stderr, "invalid value for JSON_INDENT: %d\n", indent);
-        return 2;
-    }
-    if (indent > 0)
-        flags |= JSON_INDENT(indent);
-
-    if (getenv_int("JSON_COMPACT") > 0)
-        flags |= JSON_COMPACT;
-
-    if (getenv_int("JSON_ENSURE_ASCII"))
-        flags |= JSON_ENSURE_ASCII;
-
-    if (getenv_int("JSON_PRESERVE_ORDER"))
-        flags |= JSON_PRESERVE_ORDER;
-
-    if (getenv_int("JSON_SORT_KEYS"))
-        flags |= JSON_SORT_KEYS;
-
-    precision = getenv_int("JSON_REAL_PRECISION");
-    if (precision < 0 || precision > 31) {
-        fprintf(stderr, "invalid value for JSON_REAL_PRECISION: %d\n", precision);
-        return 2;
-    }
-
-    if (getenv("HASHSEED"))
-        json_object_seed(getenv_int("HASHSEED"));
-
-    if (precision > 0)
-        flags |= JSON_REAL_PRECISION(precision);
-
-    if (getenv_int("STRIP")) {
-        /* Load to memory, strip leading and trailing whitespace */
-        size_t size = 0, used = 0;
-        char *buffer = NULL, *buf_ck = NULL;
-
-        while (1) {
-            size_t count;
-
-            size = (size == 0 ? 128 : size * 2);
-            buf_ck = realloc(buffer, size);
-            if (!buf_ck) {
-                fprintf(stderr, "Unable to allocate %d bytes\n", (int)size);
-                free(buffer);
-                return 1;
-            }
-            buffer = buf_ck;
-
-            count = fread(buffer + used, 1, size - used, stdin);
-            if (count < size - used) {
-                buffer[used + count] = '\0';
-                break;
-            }
-            used += count;
-        }
-
-        json = json_loads(strip(buffer), 0, &error);
-        free(buffer);
-    } else
-        json = json_loadf(stdin, 0, &error);
-
-    if (!json) {
-        fprintf(stderr, "%d %d %d\n%s\n", error.line, error.column, error.position,
-                error.text);
-        return 1;
-    }
-
-    json_dumpf(json, stdout, flags);
-    json_decref(json);
-
-    return 0;
-}
-
 int main(int argc, char *argv[]) {
     int i;
     char *test_path = NULL;
@@ -344,23 +248,17 @@ int main(int argc, char *argv[]) {
     for (i = 1; i < argc; i++) {
         if (!strcmp(argv[i], "--strip"))
             conf.strip = 1;
-        else if (!strcmp(argv[i], "--env"))
-            conf.use_env = 1;
         else
             test_path = argv[i];
     }
 
-    if (conf.use_env)
-        return use_env();
-    else {
-        if (!test_path)
-            goto usage;
-
-        return use_conf(test_path);
+    if (!test_path) {
+        goto usage;
     }
 
+    return use_conf(test_path);
+
 usage:
-    fprintf(stderr, "argc =%d\n", argc);
-    fprintf(stderr, "usage: %s [--strip] [--env] test_dir\n", argv[0]);
+    fprintf(stderr, "usage: %s [--strip] test_dir\n", argv[0]);
     return 2;
 }
diff --git a/test/suites/encoding-flags/run b/test/suites/encoding-flags/run
index 5db7d5e5..a6f21115 100755
--- a/test/suites/encoding-flags/run
+++ b/test/suites/encoding-flags/run
@@ -10,23 +10,13 @@ is_test() {
 }
 
 run_test() {
-    (
-        if [ -f $test_path/env ]; then
-            . $test_path/env
-        fi
-        $json_process --env <$test_path/input >$test_log/stdout 2>$test_log/stderr
-    )
+    $json_process $test_path >$test_log/stdout 2>$test_log/stderr || return 1
     valgrind_check $test_log/stderr || return 1
-    cmp -s $test_path/output $test_log/stdout
 }
 
 show_error() {
     valgrind_show_error && return
-
-    echo "EXPECTED OUTPUT:"
-    nl -bn $test_path/output
-    echo "ACTUAL OUTPUT:"
-    nl -bn $test_log/stdout
+    cat $test_log/stderr
 }
 
 . $top_srcdir/test/scripts/run-tests.sh
diff --git a/test/suites/invalid-unicode/run b/test/suites/invalid-unicode/run
index 369c43da..5b542a43 100755
--- a/test/suites/invalid-unicode/run
+++ b/test/suites/invalid-unicode/run
@@ -10,18 +10,13 @@ is_test() {
 }
 
 run_test() {
-    $json_process --env <$test_path/input >$test_log/stdout 2>$test_log/stderr
-    valgrind_check $test_log/stderr || return 1
-    cmp -s $test_path/error $test_log/stderr
+    $json_process $test_path >$test_log/stdout 2>$test_log/stderr || return 1
+    valgrind_check $test_log/stderr$s || return 1
 }
 
 show_error() {
     valgrind_show_error && return
-
-    echo "EXPECTED ERROR:"
-    nl -bn $test_path/error
-    echo "ACTUAL ERROR:"
-    nl -bn $test_log/stderr
+    cat $test_log/stderr
 }
 
 . $top_srcdir/test/scripts/run-tests.sh
diff --git a/test/suites/invalid/run b/test/suites/invalid/run
index d1d490c6..ee1ee1aa 100755
--- a/test/suites/invalid/run
+++ b/test/suites/invalid/run
@@ -13,24 +13,18 @@ do_run() {
     variant=$1
     s=".$1"
 
-    strip=0
+    strip=""
     if [ "$variant" = "strip" ]; then
         # This test should not be stripped
         [ -f $test_path/nostrip ] && return
-        strip=1
+        strip="--strip"
     fi
 
-    STRIP=$strip $json_process --env \
-        <$test_path/input >$test_log/stdout$s 2>$test_log/stderr$s
-    valgrind_check $test_log/stderr$s || return 1
-
-    ref=error
-    [ -f $test_path/error$s ] && ref=error$s
-
-    if ! cmp -s $test_path/$ref $test_log/stderr$s; then
-        echo $variant > $test_log/variant
+    if ! $json_process $strip $test_path >$test_log/stdout$s 2>$test_log/stderr$s; then
+        echo $variant >$test_log/variant
         return 1
     fi
+    valgrind_check $test_log/stderr$s || return 1
 }
 
 run_test() {
@@ -44,14 +38,7 @@ show_error() {
     s=".$variant"
 
     echo "VARIANT: $variant"
-
-    echo "EXPECTED ERROR:"
-    ref=error
-    [ -f $test_path/error$s ] && ref=error$s
-    nl -bn $test_path/$ref
-
-    echo "ACTUAL ERROR:"
-    nl -bn $test_log/stderr$s
+    cat $test_log/stderr$s
 }
 
 . $top_srcdir/test/scripts/run-tests.sh
diff --git a/test/suites/valid/run b/test/suites/valid/run
index d9954896..afc488c9 100755
--- a/test/suites/valid/run
+++ b/test/suites/valid/run
@@ -16,20 +16,14 @@ do_run() {
     variant=$1
     s=".$1"
 
-    strip=0
-    [ "$variant" = "strip" ] && strip=1
+    strip=""
+    [ "$variant" = "strip" ] && strip="--strip"
 
-    STRIP=$strip $json_process --env \
-        <$test_path/input >$test_log/stdout$s 2>$test_log/stderr$s
-    valgrind_check $test_log/stderr$s || return 1
-
-    ref=output
-    [ -f $test_path/output$s ] && ref=output$s
-
-    if ! cmp -s $test_path/$ref $test_log/stdout$s; then
-        echo $variant > $test_log/variant
+    if ! $json_process $strip $test_path >$test_log/stdout$s 2>$test_log/stderr$s; then
+        echo $variant >$test_log/variant
         return 1
     fi
+    valgrind_check $test_log/stderr$s || return 1
 }
 
 run_test() {
@@ -43,14 +37,7 @@ show_error() {
     s=".$variant"
 
     echo "VARIANT: $variant"
-
-    echo "EXPECTED OUTPUT:"
-    ref=output
-    [ -f $test_path/output$s ] && ref=output$s
-    nl -bn $test_path/$ref
-
-    echo "ACTUAL OUTPUT:"
-    nl -bn $test_log/stdout$s
+    cat $test_log/stderr$s
 }
 
 . $top_srcdir/test/scripts/run-tests.sh