diff --git a/contrib/chg/chg.c b/contrib/chg/chg.c
--- a/contrib/chg/chg.c
+++ b/contrib/chg/chg.c
@@ -220,7 +220,10 @@ static void execcmdserver(const struct c
 
 	const char **argv = mallocx(sizeof(char *) * argsize);
 	memcpy(argv, baseargv, sizeof(baseargv));
-	memcpy(argv + baseargvsize, opts->args, sizeof(char *) * opts->argsize);
+	if (opts->args) {
+		size_t size = sizeof(char *) * opts->argsize;
+		memcpy(argv + baseargvsize, opts->args, size);
+	}
 	argv[argsize - 1] = NULL;
 
 	if (putenv("CHGINTERNALMARK=") != 0)
diff --git a/mercurial/cext/bdiff.c b/mercurial/cext/bdiff.c
--- a/mercurial/cext/bdiff.c
+++ b/mercurial/cext/bdiff.c
@@ -155,12 +155,8 @@ cleanup:
 		PyEval_RestoreThread(_save);
 	PyBuffer_Release(&ba);
 	PyBuffer_Release(&bb);
-	if (al) {
-		free(al);
-	}
-	if (bl) {
-		free(bl);
-	}
+	free(al);
+	free(bl);
 	if (l.next) {
 		bdiff_freehunks(l.next);
 	}
diff --git a/mercurial/cext/manifest.c b/mercurial/cext/manifest.c
--- a/mercurial/cext/manifest.c
+++ b/mercurial/cext/manifest.c
@@ -185,15 +185,13 @@ static void lazymanifest_dealloc(lazyman
 {
 	/* free any extra lines we had to allocate */
 	int i;
-	for (i = 0; i < self->numlines; i++) {
+	for (i = 0; self->lines && (i < self->numlines); i++) {
 		if (self->lines[i].from_malloc) {
 			free(self->lines[i].start);
 		}
 	}
-	if (self->lines) {
-		free(self->lines);
-		self->lines = NULL;
-	}
+	free(self->lines);
+	self->lines = NULL;
 	if (self->pydata) {
 		Py_DECREF(self->pydata);
 		self->pydata = NULL;
diff --git a/mercurial/cext/revlog.c b/mercurial/cext/revlog.c
--- a/mercurial/cext/revlog.c
+++ b/mercurial/cext/revlog.c
@@ -333,10 +333,8 @@ static void _index_clearcaches(indexObje
 		PyMem_Free(self->offsets);
 		self->offsets = NULL;
 	}
-	if (self->nt) {
-		free(self->nt);
-		self->nt = NULL;
-	}
+	free(self->nt);
+	self->nt = NULL;
 	Py_CLEAR(self->headrevs);
 }