diff --git a/libc/string/index.c b/libc/string/index.c
index fb0492f8b..81bfba490 100644
--- a/libc/string/index.c
+++ b/libc/string/index.c
@@ -34,7 +34,7 @@ char *
 index(const char *p, int ch)
 {
 	for (;; ++p) {
-		if (*p == ch)
+		if (*p == (char) ch)
 			return((char *)p);
 		if (!*p)
 			return((char *)NULL);
diff --git a/libc/string/memrchr.c b/libc/string/memrchr.c
index a533fefe6..aeb5643b0 100644
--- a/libc/string/memrchr.c
+++ b/libc/string/memrchr.c
@@ -35,10 +35,10 @@ void *memrchr(const void *s, int c, size_t n)
         const char*  q = p + n;
 
         while (1) {
-            q--; if (q < p || q[0] == c) break;
-            q--; if (q < p || q[0] == c) break;
-            q--; if (q < p || q[0] == c) break;
-            q--; if (q < p || q[0] == c) break;
+            q--; if (q < p || q[0] == (char) c) break;
+            q--; if (q < p || q[0] == (char) c) break;
+            q--; if (q < p || q[0] == (char) c) break;
+            q--; if (q < p || q[0] == (char) c) break;
         }
         if (q >= p)
             return (void*)q;
diff --git a/libc/string/strchr.c b/libc/string/strchr.c
index 31ba4e223..9b4332c7e 100644
--- a/libc/string/strchr.c
+++ b/libc/string/strchr.c
@@ -34,7 +34,7 @@ char *
 strchr(const char *p, int ch)
 {
 	for (;; ++p) {
-		if (*p == ch)
+		if (*p == (char) ch)
 			return((char *)p);
 		if (!*p)
 			return((char *)NULL);
diff --git a/libc/string/strrchr.c b/libc/string/strrchr.c
index 4918f82db..10c07e63c 100644
--- a/libc/string/strrchr.c
+++ b/libc/string/strrchr.c
@@ -36,7 +36,7 @@ strrchr(const char *p, int ch)
 	char *save;
 
 	for (save = NULL;; ++p) {
-		if (*p == ch)
+		if (*p == (char) ch)
 			save = (char *)p;
 		if (!*p)
 			return(save);