diff --git a/lib/util/parseln.c b/lib/util/parseln.c
index 5dae211d5..892894a3f 100644
--- a/lib/util/parseln.c
+++ b/lib/util/parseln.c
@@ -23,10 +23,11 @@
 
 #include <config.h>
 
+#include <ctype.h>
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <ctype.h>
 #ifdef HAVE_STDBOOL_H
 # include <stdbool.h>
 #else
@@ -91,9 +92,20 @@ sudo_parseln_v2(char **bufp, size_t *bufsizep, unsigned int *lineno, FILE *fp, i
 
 	if (*bufp == NULL || total + len >= *bufsizep) {
 	    void *newbuf;
-	    const size_t newsize = sudo_pow2_roundup(total + len + 1);
+		const size_t size = total + len + 1;
+		const size_t newsize = sudo_pow2_roundup(size);
 
-	    if (newsize == 0 || (newbuf = realloc(*bufp, newsize)) == NULL) {
+		if (newsize < size) {
+		/* overflow */
+		errno = ENOMEM;
+		sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+		    "unable to allocate memory");
+		len = -1;
+		total = 0;
+		break;
+	    }
+		
+		if ((newbuf = realloc(*bufp, newsize)) == NULL) {
 		sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
 		    "unable to allocate memory");
 		len = -1;
diff --git a/lib/util/roundup.c b/lib/util/roundup.c
index 7caf8b454..2dd1957d6 100644
--- a/lib/util/roundup.c
+++ b/lib/util/roundup.c
@@ -47,14 +47,10 @@ sudo_pow2_roundup_v2(size_t len)
 {
     if (len < 64)
 	return 64;
-    len--;
-    len |= len >> 1;
-    len |= len >> 2;
-    len |= len >> 4;
-    len |= len >> 8;
-    len |= len >> 16;
+
 #ifdef __LP64__
-    len |= len >> 32;
+    return 1 << (64 - __builtin_clzl(len - 1));
+#else
+    return 1 << (32 - __builtin_clz(len - 1));
 #endif
-    return ++len;
 }
diff --git a/logsrvd/logsrvd_journal.c b/logsrvd/logsrvd_journal.c
index 0983d1f67..d28ad9ad5 100644
--- a/logsrvd/logsrvd_journal.c
+++ b/logsrvd/logsrvd_journal.c
@@ -270,11 +270,13 @@ journal_seek(struct timespec *target, struct connection_closure *closure)
 		bufsize = sudo_pow2_roundup(msg_len);
 		if (bufsize < msg_len) {
 		    /* overflow */
+		    errno = ENOMEM;
 		    closure->errstr = _("unable to allocate memory");
 		    break;
 		}
 		free(buf);
 		if ((buf = malloc(bufsize)) == NULL) {
+		    errno = ENOMEM;
 		    closure->errstr = _("unable to allocate memory");
 		    break;
 		}