diff --git a/include/_ctype.h b/include/_ctype.h
index a37fc1cb119..0a34886f555 100644
--- a/include/_ctype.h
+++ b/include/_ctype.h
@@ -103,9 +103,18 @@ __END_DECLS
 #endif
 
 #if defined(_USE_CTYPE_INLINE_)
+
+#ifndef EOF
+#define EOF (-1)
+#endif
+
 static __inline int
 __istype(_BSD_RUNE_T_ c, unsigned long f)
 {
+	if (c == EOF)
+		return 0;
+	if (c < 0)
+		c = (unsigned char) c;
 	return((((c & _CRMASK) ? ___runetype(c) :
 	    _CurrentRuneLocale->runetype[c]) & f) ? 1 : 0);
 }
@@ -113,6 +122,10 @@ __istype(_BSD_RUNE_T_ c, unsigned long f)
 static __inline int
 __isctype(_BSD_RUNE_T_ c, unsigned long f)
 {
+	if (c == EOF)
+		return 0;
+	if (c < 0)
+		c = (unsigned char) c;
 	return((((c & _CRMASK) ? 0 :
 	    _DefaultRuneLocale.runetype[c]) & f) ? 1 : 0);
 }
@@ -122,6 +135,10 @@ __isctype(_BSD_RUNE_T_ c, unsigned long f)
 static __inline _BSD_RUNE_T_
 toupper(_BSD_RUNE_T_ c)
 {
+	if (c == EOF)
+		return EOF;
+	if (c < 0)
+		c = (unsigned char) c;
 	return((c & _CRMASK) ?
 	    ___toupper(c) : _CurrentRuneLocale->mapupper[c]);
 }
@@ -129,6 +146,10 @@ toupper(_BSD_RUNE_T_ c)
 static __inline _BSD_RUNE_T_
 tolower(_BSD_RUNE_T_ c)
 {
+	if (c == EOF)
+		return EOF;
+	if (c < 0)
+		c = (unsigned char) c;
 	return((c & _CRMASK) ?
 	    ___tolower(c) : _CurrentRuneLocale->maplower[c]);
 }
diff --git a/include/ctype.h b/include/ctype.h
index a37fc1cb119..0a34886f555 100644
--- a/include/ctype.h
+++ b/include/ctype.h
@@ -103,9 +103,18 @@ __END_DECLS
 #endif
 
 #if defined(_USE_CTYPE_INLINE_)
+
+#ifndef EOF
+#define EOF (-1)
+#endif
+
 static __inline int
 __istype(_BSD_RUNE_T_ c, unsigned long f)
 {
+	if (c == EOF)
+		return 0;
+	if (c < 0)
+		c = (unsigned char) c;
 	return((((c & _CRMASK) ? ___runetype(c) :
 	    _CurrentRuneLocale->runetype[c]) & f) ? 1 : 0);
 }
@@ -113,6 +122,10 @@ __istype(_BSD_RUNE_T_ c, unsigned long f)
 static __inline int
 __isctype(_BSD_RUNE_T_ c, unsigned long f)
 {
+	if (c == EOF)
+		return 0;
+	if (c < 0)
+		c = (unsigned char) c;
 	return((((c & _CRMASK) ? 0 :
 	    _DefaultRuneLocale.runetype[c]) & f) ? 1 : 0);
 }
@@ -122,6 +135,10 @@ __isctype(_BSD_RUNE_T_ c, unsigned long f)
 static __inline _BSD_RUNE_T_
 toupper(_BSD_RUNE_T_ c)
 {
+	if (c == EOF)
+		return EOF;
+	if (c < 0)
+		c = (unsigned char) c;
 	return((c & _CRMASK) ?
 	    ___toupper(c) : _CurrentRuneLocale->mapupper[c]);
 }
@@ -129,6 +146,10 @@ toupper(_BSD_RUNE_T_ c)
 static __inline _BSD_RUNE_T_
 tolower(_BSD_RUNE_T_ c)
 {
+	if (c == EOF)
+		return EOF;
+	if (c < 0)
+		c = (unsigned char) c;
 	return((c & _CRMASK) ?
 	    ___tolower(c) : _CurrentRuneLocale->maplower[c]);
 }