diff --git a/bin/ch-run.c b/bin/ch-run.c
index 421bed954..99f5a6bf7 100644
--- a/bin/ch-run.c
+++ b/bin/ch-run.c
@@ -114,7 +114,6 @@ extern void warnings_reprint(void);
 const struct argp argp = { options, parse_opt, args_doc, usage };
 extern char **environ;  // see environ(7)
 extern char *warnings;
-extern const size_t warnings_size;
 
 
 /** Main **/
@@ -126,7 +125,7 @@ int main(int argc, char *argv[])
    int arg_next;
    char ** c_argv;
 
-   // initialze “warnings” buffer
+   // initialize “warnings” buffer
    warnings = mmap(NULL, warnings_size, PROT_READ | PROT_WRITE,
                    MAP_SHARED | MAP_ANONYMOUS, -1, 0);
 
diff --git a/bin/ch_misc.c b/bin/ch_misc.c
index fd5443a2f..835edd120 100644
--- a/bin/ch_misc.c
+++ b/bin/ch_misc.c
@@ -42,20 +42,16 @@ char *host_tmp = NULL;
 char *username = NULL;
 
 /* List of warnings to be re-printed on exit. This is a buffer of shared memory
-   allocated by mmap(2), structured as a sequence of
-   null-terminated character strings. Warnings that do not fit in this buffer
-   will be lost, though we allocate enough memory that this is unlikely. See
-   “warnings_append()” for more details. */
+   allocated by mmap(2), structured as a sequence of null-terminated character
+   strings. Warnings that do not fit in this buffer will be lost, though we
+   allocate enough memory that this is unlikely. See “warnings_append()” for
+   more details. */
 char *warnings;
 
 /* Current byte offset from start of “warnings” buffer. This gives the address
    where the next appended string will start. */
 size_t warnings_offset = 0;
 
-/* Size of “warnings” buffer, in bytes. We want this to be big enough that we
-   don’t need to worry about running out of room. */
-const size_t warnings_size = 4096;
-
 
 /** Function prototypes (private) **/
 
@@ -465,7 +461,8 @@ noreturn void msg_fatal(const char *file, int line, int errno_,
 void msgv(enum log_level level, const char *file, int line, int errno_,
           const char *fmt, va_list ap)
 {
-   char *message = "";
+   char *message = NULL;
+   char *ap_msg = "";
    if (level > verbose)
       return;
 
@@ -487,7 +484,6 @@ void msgv(enum log_level level, const char *file, int line, int errno_,
    if (fmt == NULL)
       fmt = "please report this bug";
 
-   char *ap_msg = "";
    T_ (1 <= vasprintf(&ap_msg, fmt, ap));
    T_ (1 <= asprintf(&message, "%s%s", message, ap_msg));
 
@@ -667,10 +663,10 @@ void version(void)
    fprintf(stderr, "%s\n", VERSION);
 }
 
-/* Append null-terminated string “str” to the memory buffer “offset” bytes away
-   from the address pointed to by “addr”. Buffer should be “size” bytes long.
-   Return the number of bytes written. If there isn’t enough room for the
-   string, do nothing and return zero. */
+/* Append null-terminated string “str” to the memory buffer “offset” bytes after
+   from the address pointed to by “addr”. Buffer length is “size” bytes. Return
+   the number of bytes written. If there isn’t enough room for the string, do
+   nothing and return zero. */
 size_t warnings_append(char *addr, char *str, size_t size, size_t offset)
 {
    size_t written = 0;
diff --git a/bin/ch_misc.h b/bin/ch_misc.h
index dbee38b4b..e74680c87 100644
--- a/bin/ch_misc.h
+++ b/bin/ch_misc.h
@@ -19,6 +19,11 @@
    and hopefully others support the following extension. */
 #define noreturn __attribute__ ((noreturn))
 
+
+/* Size of “warnings” buffer, in bytes. We want this to be big enough that we
+   don’t need to worry about running out of room. */
+#define warnings_size 4096
+
 /* Test some value, and if it's not what we expect, exit with a fatal error.
    These are macros so we have access to the file and line number.
 
@@ -105,7 +110,6 @@ extern char *host_tmp;
 extern char *username;
 extern char *warnings;
 extern size_t warnings_offset;
-extern const size_t warnings_size;
 
 
 /** Function prototypes **/
diff --git a/lib/charliecloud.py b/lib/charliecloud.py
index b9d4e2718..0e3cfaa62 100644
--- a/lib/charliecloud.py
+++ b/lib/charliecloud.py
@@ -119,7 +119,7 @@ class Download_Mode(enum.Enum):
 log_fp = sys.stderr  # File object to print logs to.
 trace_fatal = False  # Add abbreviated traceback to fatal error hint.
 
-# Warnings to be re-printed when program exists
+# Warnings to be re-printed when program exits
 warnings = []
 
 # True if the download cache is enabled.