diff --git a/embedding/browser/activex/src/pluginhostctrl/pluginsdk_include/jri_md.h b/embedding/browser/activex/src/pluginhostctrl/pluginsdk_include/jri_md.h
index 9fd61b4a63f7..00ec01bd1246 100644
--- a/embedding/browser/activex/src/pluginhostctrl/pluginsdk_include/jri_md.h
+++ b/embedding/browser/activex/src/pluginhostctrl/pluginsdk_include/jri_md.h
@@ -121,7 +121,7 @@ typedef juint			jsize;
 #endif
 
 typedef unsigned char	jbool;
-typedef char			jbyte;
+typedef signed char	jbyte;
 #ifdef IS_64 /* XXX ok for alpha, but not right on all 64-bit architectures */
 typedef unsigned int	juint;
 typedef int				jint;
diff --git a/sun-java/stubs/include/jri_md.h b/sun-java/stubs/include/jri_md.h
index cfb0ed0d9b2a..5c09a594542a 100644
--- a/sun-java/stubs/include/jri_md.h
+++ b/sun-java/stubs/include/jri_md.h
@@ -188,7 +188,7 @@ typedef struct _jobject *jref;
 #endif
 
 typedef unsigned char	jbool;
-typedef char			jbyte;
+typedef signed char	jbyte;
 #ifdef IS_64 /* XXX ok for alpha, but not right on all 64-bit architectures */
 typedef unsigned int	juint;
 typedef int				jint;