diff --git a/fuzzers/cib_file_fuzzer.c b/fuzzers/cib_file_fuzzer.c
index 579f34c8c7..1bd1d2b877 100644
--- a/fuzzers/cib_file_fuzzer.c
+++ b/fuzzers/cib_file_fuzzer.c
@@ -1,41 +1,48 @@
 /*
  * Copyright 2024 the Pacemaker project contributors
  *
  * The version control history for this file may have further details.
  *
  * This source code is licensed under the GNU Lesser General Public License
  * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
  */
+
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 
 #include <crm_internal.h>
 #include <crm/cib/internal.h>
 
 int
 LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
 {
-  char *filename;
-  int fd;
+    char *filename = NULL;
+    int fd = 0;
 
-  // Have at least some data
-  if (size < 5) {
-    return 0;
-  }
+    // Have at least some data
+    if (size < 5) {
+        return -1; // Do not add input to testing corpus
+    }
 
-  filename = crm_strdup_printf("%s/libfuzzer.XXXXXX", pcmk__get_tmpdir());
-  fd = mkstemp(filename);
-  if (fd == -1) {
-    return 0;
-  }
-  write(fd, data, size);
-  close(fd);
+    filename = crm_strdup_printf("%s/libfuzzer.XXXXXX", pcmk__get_tmpdir());
+    fd = mkstemp(filename);
+    if (fd == -1) {
+        free(filename);
+        return 0;
+    }
+    if (write(fd, data, size) < 0) {
+        close(fd);
+        unlink(filename);
+        free(filename);
+        return 0;
+    }
+    close(fd);
 
-  cib_file_read_and_verify(filename, NULL, NULL);
+    cib_file_read_and_verify(filename, NULL, NULL);
 
-  unlink(filename);
-  free(filename);
+    unlink(filename);
+    free(filename);
 
-  return 0;
+    return 0;
 }
diff --git a/fuzzers/iso8601_fuzzer.c b/fuzzers/iso8601_fuzzer.c
index cb83cb8f2a..0e151c6dbd 100644
--- a/fuzzers/iso8601_fuzzer.c
+++ b/fuzzers/iso8601_fuzzer.c
@@ -1,45 +1,46 @@
 /*
  * Copyright 2024 the Pacemaker project contributors
  *
  * The version control history for this file may have further details.
  *
  * This source code is licensed under the GNU Lesser General Public License
  * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
  */
+
 #include <stdint.h>
 #include <stdlib.h>
 #include <stdio.h>
 
 #include <crm/common/util.h>
-#include <crm/common/iso8601.h>
-#include <crm/common/iso8601_internal.h>
-
+#include <crm/common/internal.h>
 
 int
 LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
 {
-  char *ns;
-  char *result;
-  time_t epoch;
-  pcmk__time_hr_t *now;
+    char *ns = NULL;
+    char *result = NULL;
+    time_t epoch = 0;
+    pcmk__time_hr_t *now = NULL;
+    crm_time_period_t *period = NULL;
+
+    // Ensure we have enough data.
+    if (size < 10) {
+        return -1; // Do not add input to testing corpus
+    }
+    ns = pcmk__assert_alloc(1, size + 1);
+    memcpy(ns, data, size);
+
+    period = crm_time_parse_period(ns);
+    crm_time_free_period(period);
+
+    now = pcmk__time_hr_new(ns);
+    pcmk__time_hr_free(now);
+
+    now = pcmk__time_hr_now(&epoch);
+    result = pcmk__time_format_hr(ns, now);
+    pcmk__time_hr_free(now);
+    free(result);
 
-  // Ensure we have enough data.
-  if (size < 10) {
+    free(ns);
     return 0;
-  }
-  ns = malloc(size+1);
-  memcpy(ns, data, size);
-  ns[size] = '\0';
-
-  crm_time_parse_period(ns);
-  pcmk__time_hr_new(ns);
-
-  epoch = 0;
-  now = NULL;
-  now = pcmk__time_hr_now(&epoch);
-  result = pcmk__time_format_hr(ns, now);
-  free(result);
-
-  free(ns);  
-  return 0;
 }
diff --git a/fuzzers/strings_fuzzer.c b/fuzzers/strings_fuzzer.c
index 510c75fd68..f8dfc8e39f 100644
--- a/fuzzers/strings_fuzzer.c
+++ b/fuzzers/strings_fuzzer.c
@@ -1,40 +1,40 @@
 /*
  * Copyright 2024 the Pacemaker project contributors
  *
  * The version control history for this file may have further details.
  *
  * This source code is licensed under the GNU Lesser General Public License
  * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
  */
+
 #include <stdint.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <strings.h>
 #include <glib.h>
 
 #include <crm/common/options.h>
 #include <crm/common/util.h>
-#include <crm/common/util_compat.h>
-#include <crm/common/strings_internal.h>
+#include <crm/common/internal.h>
 
 int
 LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
 {
-  char *ns;
-  guint res;
+    char *ns = NULL;
+    guint res = 0U;
 
-  if (size < 10) {
-    return 0;
-  }
-  ns = malloc(size+1);
-  memcpy(ns, data, size);
-  ns[size] = '\0';
+    if (size < 10) {
+        return -1; // Do not add input to testing corpus
+    }
+    ns = pcmk__assert_alloc(1, size + 1);
+    memcpy(ns, data, size);
+    ns[size] = '\0';
 
-  pcmk__numeric_strcasecmp(ns, ns);
-  pcmk__trim(ns);
-  pcmk_parse_interval_spec(ns, &res);
-  crm_get_msec(ns);
+    pcmk__numeric_strcasecmp(ns, ns);
+    pcmk__trim(ns);
+    pcmk_parse_interval_spec(ns, &res);
+    crm_get_msec(ns);
 
-  free(ns);  
-  return 0;
+    free(ns);
+    return 0;
 }
diff --git a/fuzzers/utils_fuzzer.c b/fuzzers/utils_fuzzer.c
index 73c3f4e1d4..2cb3a5339b 100644
--- a/fuzzers/utils_fuzzer.c
+++ b/fuzzers/utils_fuzzer.c
@@ -1,34 +1,34 @@
 /*
  * Copyright 2024 the Pacemaker project contributors
  *
  * The version control history for this file may have further details.
  *
  * This source code is licensed under the GNU Lesser General Public License
  * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
  */
 
 #include <stdint.h>
 #include <stdlib.h>
 #include <stdio.h>
 
 #include <crm/common/util.h>
-#include <crm/common/util_compat.h>
+#include <crm/common/internal.h>
 
 int
 LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
 {
-  char *ns;
-  guint result;
+    char *ns = NULL;
+    guint result = 0U;
 
-  if (size < 10) {
-    return 0;
-  }
-  ns = malloc(size+1);
-  memcpy(ns, data, size);
-  ns[size] = '\0';
+    if (size < 10) {
+        return -1; // Do not add input to testing corpus
+    }
+    ns = pcmk__assert_alloc(1, size + 1);
+    memcpy(ns, data, size);
+    ns[size] = '\0';
 
-  pcmk_parse_interval_spec(ns, &result);
+    pcmk_parse_interval_spec(ns, &result);
 
-  free(ns);  
-  return 0;
+    free(ns);
+    return 0;
 }