diff --git a/lib/common/tests/utils/Makefile.am b/lib/common/tests/utils/Makefile.am
index f028ce492e..7b12fd4af7 100644
--- a/lib/common/tests/utils/Makefile.am
+++ b/lib/common/tests/utils/Makefile.am
@@ -1,30 +1,31 @@
 #
-# Copyright 2020-2023 the Pacemaker project contributors
+# Copyright 2020-2024 the Pacemaker project contributors
 #
 # The version control history for this file may have further details.
 #
 # This source code is licensed under the GNU General Public License version 2
 # or later (GPLv2+) WITHOUT ANY WARRANTY.
 #
 
 include $(top_srcdir)/mk/tap.mk
 include $(top_srcdir)/mk/unittest.mk
 
 # Add "_test" to the end of all test program names to simplify .gitignore.
 check_PROGRAMS = compare_version_test			\
 		 crm_meta_name_test			\
 		 crm_meta_value_test			\
 		 crm_user_lookup_test			\
 		 pcmk_daemon_user_test			\
 		 pcmk_str_is_infinity_test		\
 		 pcmk_str_is_minus_infinity_test 	\
 		 pcmk__fail_attr_name_test 		\
 		 pcmk__failcount_name_test 		\
 		 pcmk__getpid_s_test 			\
-		 pcmk__lastfailure_name_test
+		 pcmk__lastfailure_name_test 		\
+		 pcmk__realloc_test
 
 if WRAPPABLE_UNAME
 check_PROGRAMS += pcmk_hostname_test
 endif
 
 TESTS = $(check_PROGRAMS)
diff --git a/lib/common/tests/utils/pcmk__realloc_test.c b/lib/common/tests/utils/pcmk__realloc_test.c
new file mode 100644
index 0000000000..62d51df1f6
--- /dev/null
+++ b/lib/common/tests/utils/pcmk__realloc_test.c
@@ -0,0 +1,69 @@
+/*
+ * 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 General Public License version 2
+ * or later (GPLv2+) WITHOUT ANY WARRANTY.
+ */
+
+#include <crm_internal.h>
+
+#include <crm/common/unittest_internal.h>
+
+#include "mock_private.h"
+
+static void
+bad_size(void **state)
+{
+    char *ptr = NULL;
+
+    pcmk__assert_asserts(pcmk__realloc(ptr, 0));
+}
+
+static void
+realloc_fails(void **state)
+{
+    char *ptr = NULL;
+
+    pcmk__assert_aborts(
+        {
+            pcmk__mock_realloc = true;   // realloc() will return NULL
+            expect_any(__wrap_realloc, ptr);
+            expect_value(__wrap_realloc, size, 1000);
+            pcmk__realloc(ptr, 1000);
+            pcmk__mock_realloc = false;  // Use real realloc()
+        }
+    );
+}
+
+static void
+realloc_succeeds(void **state)
+{
+    char *ptr = NULL;
+
+    /* We can't really test that the resulting pointer is the size we asked
+     * for - it might be larger if that's what the memory allocator decides
+     * to do.  And anyway, testing realloc isn't really the point.  All we
+     * want to do here is make sure the function works when given good input.
+     */
+
+    /* Allocate new memory */
+    ptr = pcmk__realloc(ptr, 1000);
+    assert_non_null(ptr);
+
+    /* Grow previously allocated memory */
+    ptr = pcmk__realloc(ptr, 2000);
+    assert_non_null(ptr);
+
+    /* Shrink previously allocated memory */
+    ptr = pcmk__realloc(ptr, 500);
+    assert_non_null(ptr);
+
+    free(ptr);
+}
+
+PCMK__UNIT_TEST(NULL, NULL,
+                cmocka_unit_test(bad_size),
+                cmocka_unit_test(realloc_fails),
+                cmocka_unit_test(realloc_succeeds))