diff --git a/dlls/msvcp71/string.c b/dlls/msvcp71/string.c
index 534d7e7a2f3..f4e96efd622 100644
--- a/dlls/msvcp71/string.c
+++ b/dlls/msvcp71/string.c
@@ -162,7 +162,7 @@ char CDECL MSVCP_char_traits_char_to_char_type(const int *i)
 /* ?to_int_type@?$char_traits@D@std@@SAHAEBD@Z */
 int CDECL MSVCP_char_traits_char_to_int_type(const char *ch)
 {
-    return (int)*ch;
+    return (unsigned char)*ch;
 }
 
 /* ?eq_int_type@?$char_traits@D@std@@SA_NABH0@Z */
diff --git a/dlls/msvcp90/string.c b/dlls/msvcp90/string.c
index 0772adecb0a..055150c4a37 100644
--- a/dlls/msvcp90/string.c
+++ b/dlls/msvcp90/string.c
@@ -162,7 +162,7 @@ char CDECL MSVCP_char_traits_char_to_char_type(const int *i)
 /* ?to_int_type@?$char_traits@D@std@@SAHAEBD@Z */
 int CDECL MSVCP_char_traits_char_to_int_type(const char *ch)
 {
-    return (int)*ch;
+    return (unsigned char)*ch;
 }
 
 /* ?eq_int_type@?$char_traits@D@std@@SA_NABH0@Z */