diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bd83c3f64..e6a45c941 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -30,6 +30,8 @@ jobs:
       matrix:
         include:
         - SWIGLANG: ""
+          env:
+            CPPFLAGS: -DDOH_POISON
         - SWIGLANG: ""
           GCC: 7
         - SWIGLANG: ""
diff --git a/Source/DOH/doh.h b/Source/DOH/doh.h
index 7b74eac7b..af6b99664 100644
--- a/Source/DOH/doh.h
+++ b/Source/DOH/doh.h
@@ -488,7 +488,7 @@ extern void DohMemoryDebug(void);
 #define doh_internal_malloc malloc
 #define doh_internal_realloc realloc
 
-#ifdef __GNUC__
+#if defined __GNUC__ && defined DOH_POISON
 /* Use Malloc(), Realloc(), Calloc(), and Free() instead (which will exit with
  * an error rather than return NULL).
  */
@@ -496,15 +496,11 @@ extern void DohMemoryDebug(void);
 /* This works around bison's template checking if malloc and free are defined,
  * which triggers GCC's poison checks.
  */
-/*
 #  pragma GCC poison malloc free
-# pragma GCC poison realloc calloc
-*/
 # endif
+# pragma GCC poison realloc calloc
 /* Use Exit() instead (which will remove output files on error). */
-/*
 # pragma GCC poison abort exit
-*/
 #endif
 
 #endif				/* DOH_H */