diff --git a/programs/winedbg/source.c b/programs/winedbg/source.c
index c1fb2eb2d82..eb9576d08c0 100644
--- a/programs/winedbg/source.c
+++ b/programs/winedbg/source.c
@@ -70,9 +70,9 @@ void source_add_path(const char* path)
     size = strlen(path) + 1;
     if (search_path)
     {
-        unsigned pos = HeapSize(GetProcessHeap(), 0, search_path);
+        unsigned pos = strlen(search_path) + 1;
         new = HeapReAlloc(GetProcessHeap(), 0, search_path, pos + size);
-        if (!new || !pos) return;
+        if (!new) return;
         new[pos - 1] = ';';
         strcpy(&new[pos], path);
     }