diff --git a/src/include/pv.h b/src/include/pv.h
index 031f1c2..131f989 100644
--- a/src/include/pv.h
+++ b/src/include/pv.h
@@ -180,7 +180,7 @@ void pv_nanosleep(long long);
 /*
  * Set the prefix (program name) for any PV error messages.
  */
-extern void pv_set_error_prefix(/*@unique@ */ const char *);
+extern void pv_set_error_prefix(/*@null@ */ const char *);
 
 /*
  * Create a new state structure, and return it, or 0 (NULL) on error.
diff --git a/src/main/main.c b/src/main/main.c
index 2b983bf..8ba8c0e 100644
--- a/src/main/main.c
+++ b/src/main/main.c
@@ -707,6 +707,7 @@ int main(int argc, char **argv)
 		fprintf(stderr, "%s: %s: %s\n", opts->program_name, _("state allocation failed"), strerror(errno));
 		opts_free(opts);
 		debug("%s: %d", "exiting with status", PV_ERROREXIT_MEMORY);
+		pv_set_error_prefix(NULL);
 		return PV_ERROREXIT_MEMORY;
 		/*@+mustfreefresh@ */
 	}
@@ -720,6 +721,7 @@ int main(int argc, char **argv)
 		if (0 != pidfile_rc) {
 			pv_state_free(state);
 			opts_free(opts);
+			pv_set_error_prefix(NULL);
 			return pidfile_rc;
 		}
 	}
@@ -732,6 +734,7 @@ int main(int argc, char **argv)
 		if (!opts_add_file(opts, "-")) {
 			pv_state_free(state);
 			opts_free(opts);
+			pv_set_error_prefix(NULL);
 			return PV_ERROREXIT_MEMORY;
 		}
 	}
@@ -817,6 +820,7 @@ int main(int argc, char **argv)
 	if (0 != retcode) {
 		pv_state_free(state);
 		opts_free(opts);
+		pv_set_error_prefix(NULL);
 		return retcode;
 	}
 
@@ -867,6 +871,7 @@ int main(int argc, char **argv)
 			pv_sig_fini(state);
 			pv_state_free(state);
 			opts_free(opts);
+			pv_set_error_prefix(NULL);
 			return retcode;
 		}
 		/* As above - no ETA if the size is unknown. */
@@ -974,6 +979,9 @@ int main(int argc, char **argv)
 	/* Free the data from parsing the command-line arguments. */
 	opts_free(opts);
 
+	/* Clear the error message prefix. */
+	pv_set_error_prefix(NULL);
+
 	debug("%s: %d", "exiting with status", retcode);
 
 	return retcode;
diff --git a/src/pv/display.c b/src/pv/display.c
index 2538dac..c933a92 100644
--- a/src/pv/display.c
+++ b/src/pv/display.c
@@ -50,41 +50,30 @@
 #endif
 
 /*
- * The error prefix for messages (the program name); whether it has been
- * set; and whether any output has been displayed yet, indicating whether
- * any errors must be preceded by a newline.
+ * The error prefix for messages (the program name); and whether any output
+ * has been displayed yet, indicating whether any errors must be preceded by
+ * a newline.
  */
-/* TODO: make pv__error_prefix a dynamic buffer. */
-static char pv__error_prefix[64];	 /* flawfinder: ignore */
-static bool pv__error_prefix_set = false;
+/*@only@ */ static /*@null@ */ char * pv__error_prefix = NULL;
 static bool pv__output_produced = false;
 
-/*
- * flawfinder rationale: zeroed before use, string copy is bounded to 1 less
- * than size so it always has \0 termination.  Not used unless initialised,
- * by checking pv__error_prefix_set.
- */
 
 /*
- * Set the error message prefix.
+ * Set the error message prefix.  If the new prefix is NULL, the current
+ * prefix is cleared.
  */
-void pv_set_error_prefix( /*@unique@ */ const char *prefix)
+void pv_set_error_prefix( /*@null@ */ const char *prefix)
 {
+	if (NULL != pv__error_prefix) {
+		free(pv__error_prefix);
+		pv__error_prefix = NULL;
+	}
 	if (NULL == prefix)
 		return;
-	memset(pv__error_prefix, 0, sizeof(pv__error_prefix));
-	strncpy(pv__error_prefix, prefix, sizeof(pv__error_prefix) - 1);	/* flawfinder: ignore */
-	pv__error_prefix_set = true;
-	/*
-	 * flawfinder rationale: strncpy's pointers are as valid as they can
-	 * be since the first is a static buffer and the second is
-	 * caller-supplied.  The caller must \0-terminate the string but in
-	 * any case it is bounded to 1 less than the size of the
-	 * destination.  The destination is zeroed before use so the result
-	 * is guaranteed to be \0-terminated.
-	 */
+	pv__error_prefix = pv_strdup(prefix);
 }
 
+
 /*
  * Output an error message.  If anything has been sent to the terminal
  * already, then put a newline before the message, to avoid writing over
@@ -95,7 +84,7 @@ void pv_error(char *format, ...)
 	va_list ap;
 	if (pv__output_produced)
 		fprintf(stderr, "\n");
-	if (pv__error_prefix_set)
+	if (NULL != pv__error_prefix)
 		fprintf(stderr, "%s: ", pv__error_prefix);
 	va_start(ap, format);
 	(void) vfprintf(stderr, format, ap);	/* flawfinder: ignore */