diff --git a/Makefile b/Makefile
index ff21459..57b2544 100644
--- a/Makefile
+++ b/Makefile
@@ -128,7 +128,7 @@ qrap: $(QRAP_SRCS) passt.h
 valgrind: EXTRA_SYSCALLS += rt_sigprocmask rt_sigtimedwait rt_sigaction	\
 			    getpid gettid kill clock_gettime mmap	\
 			    munmap open unlink gettimeofday futex
-valgrind: FLAGS:=-g -O0 $(filter-out -O%,$(FLAGS))
+valgrind: FLAGS:=-g -O0 $(filter-out -O%,$(FLAGS)) -DVALGRIND
 valgrind: all
 
 .PHONY: clean
diff --git a/tcp.c b/tcp.c
index a0e577d..40e3dec 100644
--- a/tcp.c
+++ b/tcp.c
@@ -2097,6 +2097,15 @@ static void tcp_conn_from_tap(struct ctx *c,
  *
  * Return: 0 on success, negative error code from recv() on failure
  */
+#ifdef VALGRIND
+/* valgrind doesn't realise that passing a NULL buffer to recv() is ok if using
+ * MSG_TRUNC.  We have a suppression for this in the tests, but it relies on
+ * valgrind being able to see the tcp_sock_consume() stack frame, which it won't
+ * if this gets inlined.  This has a single caller making it a likely inlining
+ * candidate, and certain compiler versions will do so even at -O0.
+ */
+ __attribute__((noinline))
+#endif /* VALGRIND */
 static int tcp_sock_consume(const struct tcp_tap_conn *conn, uint32_t ack_seq)
 {
 	/* Simply ignore out-of-order ACKs: we already consumed the data we
diff --git a/test/valgrind.supp b/test/valgrind.supp
index 1228056..a158394 100644
--- a/test/valgrind.supp
+++ b/test/valgrind.supp
@@ -3,7 +3,6 @@
    passt_recv_MSG_TRUNC_into_NULL_buffer
    Memcheck:Param
    socketcall.recvfrom(buf)
-   fun:recv
    ...
-   fun:tcp_sock_consume*
+   fun:tcp_sock_consume
 }