diff --git a/lib/libc/regex/engine.c b/lib/libc/regex/engine.c
index d31ccaf74d2..dc7f2a6761d 100644
--- a/lib/libc/regex/engine.c
+++ b/lib/libc/regex/engine.c
@@ -398,7 +398,7 @@ dissect(struct match *m,
 			es += OPND(m->g->strip[es]);
 			break;
 		case OCH_:
-			while (OP(m->g->strip[es]) != O_CH)
+			while (OP(m->g->strip[es]) != (sop)O_CH)
 				es += OPND(m->g->strip[es]);
 			break;
 		}
@@ -512,7 +512,7 @@ dissect(struct match *m,
 				assert(OP(m->g->strip[esub]) == OOR2);
 				ssub = esub + 1;
 				esub += OPND(m->g->strip[esub]);
-				if (OP(m->g->strip[esub]) == OOR2)
+				if (OP(m->g->strip[esub]) == (sop)OOR2)
 					esub--;
 				else
 					assert(OP(m->g->strip[esub]) == O_CH);
@@ -647,7 +647,7 @@ backref(struct match *m,
 			do {
 				assert(OP(s) == OOR2);
 				ss += OPND(s);
-			} while (OP(s = m->g->strip[ss]) != O_CH);
+			} while (OP(s = m->g->strip[ss]) != (sop)O_CH);
 			/* note that the ss++ gets us past the O_CH */
 			break;
 		default:	/* have to make a choice */
@@ -680,7 +680,7 @@ backref(struct match *m,
 		ssp = m->offp + m->pmatch[i].rm_so;
 		if (memcmp(sp, ssp, len) != 0)
 			return(NULL);
-		while (m->g->strip[ss] != SOP(O_BACK, i))
+		while (m->g->strip[ss] != (sop)SOP(O_BACK, i))
 			ss++;
 		return(backref(m, sp+len, stop, ss+1, stopst, lev, rec));
 	case OQUEST_:		/* to null or not */
@@ -712,13 +712,13 @@ backref(struct match *m,
 			if (dp != NULL)
 				return(dp);
 			/* that one missed, try next one */
-			if (OP(m->g->strip[esub]) == O_CH)
+			if (OP(m->g->strip[esub]) == (sop)O_CH)
 				return(NULL);	/* there is none */
 			esub++;
-			assert(OP(m->g->strip[esub]) == OOR2);
+			assert(OP(m->g->strip[esub]) == (sop)OOR2);
 			ssub = esub + 1;
 			esub += OPND(m->g->strip[esub]);
-			if (OP(m->g->strip[esub]) == OOR2)
+			if (OP(m->g->strip[esub]) == (sop)OOR2)
 				esub--;
 			else
 				assert(OP(m->g->strip[esub]) == O_CH);
@@ -847,7 +847,7 @@ walk(struct match *m, const char *start, const char *stop, sopno startst,
 			else
 				matchp = p;
 		}
-		if (EQ(st, empty) || p == stop || clen > stop - p)
+		if (EQ(st, empty) || p == stop || clen > (size_t)(stop - p))
 			break;		/* NOTE BREAK OUT */
 
 		/* no, we must deal with this character */
@@ -969,22 +969,22 @@ step(struct re_guts *g,
 			break;
 		case OCH_:		/* mark the first two branches */
 			FWD(aft, aft, 1);
-			assert(OP(g->strip[pc+OPND(s)]) == OOR2);
+			assert(OP(g->strip[pc+OPND(s)]) == (sop)OOR2);
 			FWD(aft, aft, OPND(s));
 			break;
 		case OOR1:		/* done a branch, find the O_CH */
 			if (ISSTATEIN(aft, here)) {
 				for (look = 1;
-						OP(s = g->strip[pc+look]) != O_CH;
-						look += OPND(s))
-					assert(OP(s) == OOR2);
+				    OP(s = g->strip[pc+look]) != (sop)O_CH;
+				    look += OPND(s))
+					assert(OP(s) == (sop)OOR2);
 				FWD(aft, aft, look + 1);
 			}
 			break;
 		case OOR2:		/* propagate OCH_'s marking */
 			FWD(aft, aft, 1);
-			if (OP(g->strip[pc+OPND(s)]) != O_CH) {
-				assert(OP(g->strip[pc+OPND(s)]) == OOR2);
+			if (OP(g->strip[pc+OPND(s)]) != (sop)O_CH) {
+				assert(OP(g->strip[pc+OPND(s)]) == (sop)OOR2);
 				FWD(aft, aft, OPND(s));
 			}
 			break;
diff --git a/lib/libc/regex/regcomp.c b/lib/libc/regex/regcomp.c
index e460e145636..37d37a9bc52 100644
--- a/lib/libc/regex/regcomp.c
+++ b/lib/libc/regex/regcomp.c
@@ -364,6 +364,7 @@ p_ere_exp(struct parse *p, struct branchc *bc)
 	sopno subno;
 	int wascaret = 0;
 
+	(void)bc;
 	assert(MORE());		/* caller should have ensured this */
 	c = GETNEXT();
 
@@ -534,6 +535,7 @@ p_branch_eat_delim(struct parse *p, struct branchc *bc)
 {
 	int nskip;
 
+	(void)bc;
 	nskip = 0;
 	while (EAT('|'))
 		++nskip;
@@ -587,6 +589,7 @@ static bool
 p_branch_empty(struct parse *p, struct branchc *bc)
 {
 
+	(void)bc;
 	SETERROR(REG_EMPTY);
 	return (false);
 }
@@ -1617,12 +1620,12 @@ findmust(struct parse *p, struct re_guts *g)
 				scan += OPND(s);
 				s = *scan;
 				/* assert() interferes w debug printouts */
-				if (OP(s) != O_QUEST && OP(s) != O_CH &&
-							OP(s) != OOR2) {
+				if (OP(s) != (sop)O_QUEST &&
+				    OP(s) != (sop)O_CH && OP(s) != (sop)OOR2) {
 					g->iflags |= BAD;
 					return;
 				}
-			} while (OP(s) != O_QUEST && OP(s) != O_CH);
+			} while (OP(s) != (sop)O_QUEST && OP(s) != (sop)O_CH);
 			/* FALLTHROUGH */
 		case OBOW:		/* things that break a sequence */
 		case OEOW:
@@ -1631,7 +1634,7 @@ findmust(struct parse *p, struct re_guts *g)
 		case O_QUEST:
 		case O_CH:
 		case OEND:
-			if (newlen > g->mlen) {		/* ends one */
+			if (newlen > (sopno)g->mlen) {		/* ends one */
 				start = newstart;
 				g->mlen = newlen;
 				if (offset > -1) {
@@ -1646,7 +1649,7 @@ findmust(struct parse *p, struct re_guts *g)
 			newlen = 0;
 			break;
 		case OANY:
-			if (newlen > g->mlen) {		/* ends one */
+			if (newlen > (sopno)g->mlen) {		/* ends one */
 				start = newstart;
 				g->mlen = newlen;
 				if (offset > -1) {
@@ -1664,7 +1667,7 @@ findmust(struct parse *p, struct re_guts *g)
 			break;
 		case OANYOF:		/* may or may not invalidate offset */
 			/* First, everything as OANY */
-			if (newlen > g->mlen) {		/* ends one */
+			if (newlen > (sopno)g->mlen) {		/* ends one */
 				start = newstart;
 				g->mlen = newlen;
 				if (offset > -1) {
@@ -1687,7 +1690,7 @@ findmust(struct parse *p, struct re_guts *g)
 			 * save the last known good offset, in case the
 			 * must sequence doesn't occur later.
 			 */
-			if (newlen > g->mlen) {		/* ends one */
+			if (newlen > (sopno)g->mlen) {		/* ends one */
 				start = newstart;
 				g->mlen = newlen;
 				if (offset > -1)
@@ -1748,7 +1751,7 @@ altoffset(sop *scan, int offset)
 	largest = 0;
 	try = 0;
 	s = *scan++;
-	while (OP(s) != O_QUEST && OP(s) != O_CH) {
+	while (OP(s) != (sop)O_QUEST && OP(s) != (sop)O_CH) {
 		switch (OP(s)) {
 		case OOR1:
 			if (try > largest)
@@ -1764,10 +1767,10 @@ altoffset(sop *scan, int offset)
 			do {
 				scan += OPND(s);
 				s = *scan;
-				if (OP(s) != O_QUEST && OP(s) != O_CH &&
-							OP(s) != OOR2)
+				if (OP(s) != (sop)O_QUEST &&
+				    OP(s) != (sop)O_CH && OP(s) != (sop)OOR2)
 					return -1;
-			} while (OP(s) != O_QUEST && OP(s) != O_CH);
+			} while (OP(s) != (sop)O_QUEST && OP(s) != (sop)O_CH);
 			/* We must skip to the next position, or we'll
 			 * leave altoffset() too early.
 			 */