diff --git a/dlls/jscript/jsstr.c b/dlls/jscript/jsstr.c
index 20e6760ec82..a9dfc49d876 100644
--- a/dlls/jscript/jsstr.c
+++ b/dlls/jscript/jsstr.c
@@ -22,25 +22,25 @@
 
 const char *debugstr_jsstr(jsstr_t *str)
 {
-    return debugstr_wn(str->str, jsstr_length(str));
+    return debugstr_wn(jsstr_as_inline(str)->buf, jsstr_length(str));
 }
 
 WCHAR *jsstr_alloc_buf(unsigned len, jsstr_t **r)
 {
-    jsstr_t *ret;
+    jsstr_inline_t *ret;
 
     if(len > JSSTR_MAX_LENGTH)
         return NULL;
 
-    ret = heap_alloc(FIELD_OFFSET(jsstr_t, str[len+1]));
+    ret = heap_alloc(FIELD_OFFSET(jsstr_inline_t, buf[len+1]));
     if(!ret)
         return NULL;
 
-    ret->length_flags = len << JSSTR_LENGTH_SHIFT;
-    ret->ref = 1;
-    ret->str[len] = 0;
-    *r = ret;
-    return ret->str;
+    ret->str.length_flags = len << JSSTR_LENGTH_SHIFT;
+    ret->str.ref = 1;
+    ret->buf[len] = 0;
+    *r = &ret->str;
+    return ret->buf;
 }
 
 jsstr_t *jsstr_alloc_len(const WCHAR *buf, unsigned len)
@@ -61,7 +61,7 @@ int jsstr_cmp(jsstr_t *str1, jsstr_t *str2)
     int len2 = jsstr_length(str2);
     int ret;
 
-    ret = memcmp(str1->str, str2->str, min(len1, len2)*sizeof(WCHAR));
+    ret = memcmp(jsstr_as_inline(str1)->buf, jsstr_as_inline(str2)->buf, min(len1, len2)*sizeof(WCHAR));
     if(!ret)
         ret = len1 - len2;
 
diff --git a/dlls/jscript/jsstr.h b/dlls/jscript/jsstr.h
index 28742ac38f0..4d005dceeb6 100644
--- a/dlls/jscript/jsstr.h
+++ b/dlls/jscript/jsstr.h
@@ -19,7 +19,6 @@
 struct _jsstr_t {
     unsigned length_flags;
     unsigned ref;
-    WCHAR str[1];
 };
 
 #define JSSTR_LENGTH_SHIFT 4
@@ -33,6 +32,11 @@ static inline unsigned jsstr_length(jsstr_t *str)
     return str->length_flags >> JSSTR_LENGTH_SHIFT;
 }
 
+typedef struct {
+    jsstr_t str;
+    WCHAR buf[1];
+} jsstr_inline_t;
+
 jsstr_t *jsstr_alloc_len(const WCHAR*,unsigned) DECLSPEC_HIDDEN;
 WCHAR *jsstr_alloc_buf(unsigned,jsstr_t**) DECLSPEC_HIDDEN;
 
@@ -53,27 +57,32 @@ static inline jsstr_t *jsstr_addref(jsstr_t *str)
     return str;
 }
 
+static inline jsstr_inline_t *jsstr_as_inline(jsstr_t *str)
+{
+    return CONTAINING_RECORD(str, jsstr_inline_t, str);
+}
+
 /* This will be failable in the future. */
 static inline const WCHAR *jsstr_flatten(jsstr_t *str)
 {
-    return str->str;
+    return jsstr_as_inline(str)->buf;
 }
 
 static inline BOOL jsstr_eq(jsstr_t *str1, jsstr_t *str2)
 {
     unsigned len = jsstr_length(str1);
-    return len == jsstr_length(str2) && !memcmp(str1->str, str2->str, len*sizeof(WCHAR));
+    return len == jsstr_length(str2) && !memcmp(jsstr_as_inline(str1)->buf, jsstr_as_inline(str2)->buf, len*sizeof(WCHAR));
 }
 
 static inline void jsstr_extract(jsstr_t *str, unsigned off, unsigned len, WCHAR *buf)
 {
-    memcpy(buf, str->str+off, len*sizeof(WCHAR));
+    memcpy(buf, jsstr_as_inline(str)->buf+off, len*sizeof(WCHAR));
 }
 
 static inline unsigned jsstr_flush(jsstr_t *str, WCHAR *buf)
 {
     unsigned len = jsstr_length(str);
-    memcpy(buf, str->str, len*sizeof(WCHAR));
+    memcpy(buf, jsstr_as_inline(str)->buf, len*sizeof(WCHAR));
     return len;
 }