diff --git a/src/spx_php.c b/src/spx_php.c
index f56ef40..ad951d6 100644
--- a/src/spx_php.c
+++ b/src/spx_php.c
@@ -346,7 +346,7 @@ char * spx_php_build_command_line(void)
         goto error;
     }
 
-    spx_str_builder_t * str_builder = spx_str_builder_create(1024);
+    spx_str_builder_t * str_builder = spx_str_builder_create(2 * 1024);
     if (!str_builder) {
         goto error;
     }
diff --git a/src/spx_str_builder.c b/src/spx_str_builder.c
index ef3a655..959f0ae 100644
--- a/src/spx_str_builder.c
+++ b/src/spx_str_builder.c
@@ -233,10 +233,10 @@ size_t spx_str_builder_append_str(spx_str_builder_t * str_builder, const char *
 
         p[c++] = *str;
         str++;
+        str_builder->size++;
     }
 
     p[c] = 0;
-    str_builder->size += c;
 
     return c;
 }