diff --git a/tests/libtest/first.h b/tests/libtest/first.h
index 5b3ee2d448..062cd169be 100644
--- a/tests/libtest/first.h
+++ b/tests/libtest/first.h
@@ -43,10 +43,6 @@ extern const struct entry_s s_entries[];
 
 extern int unitfail; /* for unittests */
 
-#ifdef UNITTESTS
-#include "unitprotos.h"
-#endif
-
 #include "curlx/base64.h" /* for curlx_base64* */
 #include "curlx/dynbuf.h" /* for curlx_dyn_*() */
 #include "curlx/fopen.h" /* for curlx_f*() */
diff --git a/tests/libtest/unitcheck.h b/tests/libtest/unitcheck.h
index fa71757fb9..462f8b45f3 100644
--- a/tests/libtest/unitcheck.h
+++ b/tests/libtest/unitcheck.h
@@ -23,6 +23,10 @@
  ***************************************************************************/
 #include "first.h"
 
+#ifdef BUILDING_LIBCURL
+#include "unitprotos.h"
+#endif
+
 /* The fail macros mark the current test step as failed, and continue */
 #define fail_if(expr, msg)                                             \
   do {                                                                 \