diff --git a/dlls/msvcrt/string.c b/dlls/msvcrt/string.c
index b2bc3e9c2e6..31ed4e21811 100644
--- a/dlls/msvcrt/string.c
+++ b/dlls/msvcrt/string.c
@@ -549,8 +549,10 @@ static double strtod16(MSVCRT_wchar_t get(void *ctx), void unget(void *ctx),
         }
         if(nch>='0' && nch<='9') {
             while(nch>='0' && nch<='9') {
-                if(e>INT_MAX/10 || (e=e*10+nch-'0')<0)
+                if(e>INT_MAX/10 || e*10>INT_MAX-nch+'0')
                     e = INT_MAX;
+                else
+                    e = e*10+nch-'0';
                 nch = get(ctx);
             }
             if((nch!=MSVCRT_WEOF) && (nch < '0' || nch > '9')) unget(ctx);
@@ -827,8 +829,10 @@ double parse_double(MSVCRT_wchar_t (*get)(void *ctx), void (*unget)(void *ctx),
 
         if(nch>='0' && nch<='9') {
             while(nch>='0' && nch<='9') {
-                if(e>INT_MAX/10 || (e=e*10+nch-'0')<0)
+                if(e>INT_MAX/10 || e*10>INT_MAX-nch+'0')
                     e = INT_MAX;
+                else
+                    e = e*10+nch-'0';
                 nch = get(ctx);
             }
             if(nch != MSVCRT_WEOF) unget(ctx);