diff --git a/ed25519/ref10/fe_isnonzero.c b/ed25519/ref10/fe_isnonzero.c
index 4756800..0261e92 100644
--- a/ed25519/ref10/fe_isnonzero.c
+++ b/ed25519/ref10/fe_isnonzero.c
@@ -9,7 +9,7 @@ Preconditions:
    |f| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc.
 */
 
-static const unsigned char zero[32];
+static const unsigned char zero[32] = {0};
 
 int fe_isnonzero(const fe f)
 {
diff --git a/filters.h b/filters.h
index 93ed3d2..7c55807 100644
--- a/filters.h
+++ b/filters.h
@@ -409,7 +409,7 @@ static void filters_add(const char *filter)
 	memset(&f,0,sizeof(f));
 	f.re = re;
 	size_t fl = strlen(filter) + 1;
-	f.str = malloc(fl);
+	f.str = (char *) malloc(fl);
 	if (!f.str)
 		abort();
 	memcpy(f.str,filter,fl);
diff --git a/main.c b/main.c
index ce4a9d5..d3f77ac 100644
--- a/main.c
+++ b/main.c
@@ -217,7 +217,7 @@ static void *dowork(void *task)
 	memcpy(hashsrc,checksumstr,checksumstrlen);
 	hashsrc[checksumstrlen + PUBLIC_LEN] = 0x03; // version
 
-	sname = malloc(workdirlen + ONIONLEN + 63 + 1);
+	sname = (char *) malloc(workdirlen + ONIONLEN + 63 + 1);
 	if (!sname)
 		abort();
 	if (workdir)
@@ -326,7 +326,7 @@ static void *dofastwork(void *task)
 	memcpy(hashsrc,checksumstr,checksumstrlen);
 	hashsrc[checksumstrlen + PUBLIC_LEN] = 0x03; // version
 
-	sname = malloc(workdirlen + ONIONLEN + 63 + 1);
+	sname = (char *) malloc(workdirlen + ONIONLEN + 63 + 1);
 	if (!sname)
 		abort();
 	if (workdir)
@@ -463,7 +463,7 @@ static void setworkdir(const char *wd)
 	unsigned needslash = 0;
 	if (wd[l-1] != '/')
 		needslash = 1;
-	char *s = malloc(l + needslash + 1);
+	char *s = (char *) malloc(l + needslash + 1);
 	if (!s)
 		abort();
 	memcpy(s,wd,l);