diff --git a/dlls/mshtml/editor.c b/dlls/mshtml/editor.c
index 75a69976fed..0a1b4879bde 100644
--- a/dlls/mshtml/editor.c
+++ b/dlls/mshtml/editor.c
@@ -822,7 +822,7 @@ static HRESULT exec_composesettings(HTMLDocumentNode *doc, DWORD cmdexecopt, VAR
     if(!ptr)
         return S_OK;
 
-    if(iswdigit(*++ptr)) {
+    if(is_digit(*++ptr)) {
         VARIANT v;
 
         V_VT(&v) = VT_I4;
diff --git a/dlls/mshtml/htmlbody.c b/dlls/mshtml/htmlbody.c
index 1d032d62d30..981d93f9b41 100644
--- a/dlls/mshtml/htmlbody.c
+++ b/dlls/mshtml/htmlbody.c
@@ -95,7 +95,7 @@ static int comp_value(const WCHAR *ptr, int dpc)
     while(dpc--) {
         if(!*ptr)
             ret *= 16;
-        else if(iswdigit(ch = *ptr++))
+        else if(is_digit(ch = *ptr++))
             ret = ret*16 + (ch-'0');
         else if('a' <= ch && ch <= 'f')
             ret = ret*16 + (ch-'a') + 10;
diff --git a/dlls/mshtml/htmlelem.c b/dlls/mshtml/htmlelem.c
index 49126935b30..a594337eadc 100644
--- a/dlls/mshtml/htmlelem.c
+++ b/dlls/mshtml/htmlelem.c
@@ -700,7 +700,7 @@ static HRESULT HTMLRectCollection_get_dispid(DispatchEx *dispex, BSTR name, DWOR
     DWORD idx = 0;
     WCHAR *ptr;
 
-    for(ptr = name; *ptr && iswdigit(*ptr); ptr++)
+    for(ptr = name; *ptr && is_digit(*ptr); ptr++)
         idx = idx*10 + (*ptr-'0');
     if(*ptr)
         return DISP_E_UNKNOWNNAME;
@@ -6061,7 +6061,7 @@ static HRESULT HTMLFiltersCollection_get_dispid(DispatchEx *dispex, BSTR name, D
     WCHAR *ptr;
     int idx = 0;
 
-    for(ptr = name; *ptr && iswdigit(*ptr); ptr++)
+    for(ptr = name; *ptr && is_digit(*ptr); ptr++)
         idx = idx*10 + (*ptr-'0');
     if(*ptr)
         return DISP_E_UNKNOWNNAME;
diff --git a/dlls/mshtml/htmlelemcol.c b/dlls/mshtml/htmlelemcol.c
index 62c7254c775..51cc90110f6 100644
--- a/dlls/mshtml/htmlelemcol.c
+++ b/dlls/mshtml/htmlelemcol.c
@@ -562,7 +562,7 @@ static HRESULT HTMLElementCollection_get_dispid(DispatchEx *dispex, BSTR name, D
     if(!*name)
         return DISP_E_UNKNOWNNAME;
 
-    for(ptr = name; *ptr && iswdigit(*ptr); ptr++)
+    for(ptr = name; *ptr && is_digit(*ptr); ptr++)
         idx = idx*10 + (*ptr-'0');
 
     if(*ptr) {
diff --git a/dlls/mshtml/htmlnode.c b/dlls/mshtml/htmlnode.c
index faffb6bd025..d80c615e726 100644
--- a/dlls/mshtml/htmlnode.c
+++ b/dlls/mshtml/htmlnode.c
@@ -373,7 +373,7 @@ static HRESULT HTMLDOMChildrenCollection_get_dispid(DispatchEx *dispex, BSTR nam
     DWORD idx=0;
     UINT32 len = 0;
 
-    for(ptr = name; *ptr && iswdigit(*ptr); ptr++)
+    for(ptr = name; *ptr && is_digit(*ptr); ptr++)
         idx = idx*10 + (*ptr-'0');
     if(*ptr)
         return DISP_E_UNKNOWNNAME;
diff --git a/dlls/mshtml/htmlselect.c b/dlls/mshtml/htmlselect.c
index 21d4fc7acb1..739da9bf0ff 100644
--- a/dlls/mshtml/htmlselect.c
+++ b/dlls/mshtml/htmlselect.c
@@ -1190,7 +1190,7 @@ static HRESULT HTMLSelectElement_get_dispid(HTMLDOMNode *iface, BSTR name, DWORD
     const WCHAR *ptr;
     DWORD idx = 0;
 
-    for(ptr = name; *ptr && iswdigit(*ptr); ptr++) {
+    for(ptr = name; *ptr && is_digit(*ptr); ptr++) {
         idx = idx*10 + (*ptr-'0');
         if(idx > MSHTML_CUSTOM_DISPID_CNT) {
             WARN("too big idx\n");
diff --git a/dlls/mshtml/htmlstyle.c b/dlls/mshtml/htmlstyle.c
index 39fd489bdaf..15e2f263035 100644
--- a/dlls/mshtml/htmlstyle.c
+++ b/dlls/mshtml/htmlstyle.c
@@ -871,7 +871,7 @@ static void fix_px_value(nsAString *nsstr)
         if(!*ptr)
             break;
 
-        while(*ptr && iswdigit(*ptr))
+        while(*ptr && is_digit(*ptr))
             ptr++;
 
         if(!*ptr || iswspace(*ptr)) {
@@ -1096,7 +1096,7 @@ static HRESULT get_nsstyle_property_var(nsIDOMCSSStyleDeclaration *nsstyle, styl
             ptr++;
         }
 
-        while(iswdigit(*ptr))
+        while(is_digit(*ptr))
             i = i*10 + (*ptr++ - '0');
 
         if(!*ptr) {
@@ -1228,7 +1228,7 @@ static HRESULT get_nsstyle_pixel_val(HTMLStyle *This, styleid_t sid, LONG *p)
 
             if(*ptr == '.') {
                 /* Skip all digits. We have tests showing that we should not round the value. */
-                while(iswdigit(*++ptr));
+                while(is_digit(*++ptr));
             }
         }
 
@@ -2953,11 +2953,11 @@ static void update_filter(HTMLStyle *This)
 
                     ptr2 += ARRAY_SIZE(opacityW);
 
-                    while(iswdigit(*ptr2))
+                    while(is_digit(*ptr2))
                         fval = fval*10.0f + (float)(*ptr2++ - '0');
 
                     if(*ptr2 == '.') {
-                        while(iswdigit(*++ptr2)) {
+                        while(is_digit(*++ptr2)) {
                             fval += e * (float)(*ptr2++ - '0');
                             e *= 0.1f;
                         }
diff --git a/dlls/mshtml/htmltable.c b/dlls/mshtml/htmltable.c
index 972a2175bb3..a37ab354132 100644
--- a/dlls/mshtml/htmltable.c
+++ b/dlls/mshtml/htmltable.c
@@ -1021,9 +1021,9 @@ static HRESULT nsstr_to_truncated_bstr(const nsAString *nsstr, BSTR *ret_ptr)
 
     nsAString_GetData(nsstr, &str);
 
-    for(ptr = str; iswdigit(*ptr); ptr++);
+    for(ptr = str; is_digit(*ptr); ptr++);
     if(*ptr == '.') {
-        for(end = ptr++; iswdigit(*ptr); ptr++);
+        for(end = ptr++; is_digit(*ptr); ptr++);
         if(*ptr)
             end = NULL;
     }
diff --git a/dlls/mshtml/mshtml_private.h b/dlls/mshtml/mshtml_private.h
index 441da2019c8..9612b326088 100644
--- a/dlls/mshtml/mshtml_private.h
+++ b/dlls/mshtml/mshtml_private.h
@@ -1363,6 +1363,11 @@ static inline VARIANT_BOOL variant_bool(BOOL b)
     return b ? VARIANT_TRUE : VARIANT_FALSE;
 }
 
+static inline BOOL is_digit(WCHAR c)
+{
+    return '0' <= c && c <= '9';
+}
+
 #ifdef __i386__
 extern void *call_thiscall_func;
 #endif
diff --git a/dlls/mshtml/mutation.c b/dlls/mshtml/mutation.c
index 6903fe8652f..96490f9abd9 100644
--- a/dlls/mshtml/mutation.c
+++ b/dlls/mshtml/mutation.c
@@ -109,16 +109,16 @@ static PRUnichar *handle_insert_comment(HTMLDocumentNode *doc, const PRUnichar *
     while(iswspace(*ptr))
         ptr++;
 
-    if(!iswdigit(*ptr))
+    if(!is_digit(*ptr))
         return NULL;
-    while(iswdigit(*ptr))
+    while(is_digit(*ptr))
         majorv = majorv*10 + (*ptr++ - '0');
 
     if(*ptr == '.') {
         ptr++;
-        if(!iswdigit(*ptr))
+        if(!is_digit(*ptr))
             return NULL;
-        while(iswdigit(*ptr))
+        while(is_digit(*ptr))
             minorv = minorv*10 + (*ptr++ - '0');
     }