diff --git a/Makefile b/Makefile
index 36a66ea..bccceb5 100644
--- a/Makefile
+++ b/Makefile
@@ -48,22 +48,22 @@
 	@find src/ -name *.c -o -name *.cc -o -name *.h | xargs clang-format -style file -i
 	@find inc/ -name *.c -o -name *.cc -o -name *.h | xargs clang-format -style file -i
 	@find test/ -name *.c -o -name *.cc -o -name *.h | xargs clang-format -style file -i
-	@find . \( -name *.gn -o -name *.gni \) -exec $(GN) format {} \;
+	@find . \( -name *.gn -o -name *.gni \) | xargs -n1 $(GN) format
 
 # see .clang-tidy.
 .PHONY: tidy
 tidy: $(OUT_DIR)/build.ninja
 	@$(NINJA) -C $(OUT_DIR)
 	@echo "Tidying..."
-	@find src/ \( -name *.c -o -name *.cc \) -exec clang-tidy -p $(OUT_DIR) -fix {} \;
-	@find test/ \( -name *.c -o -name *.cc \) -exec clang-tidy -p $(OUT_DIR) -fix {} \;
+	@find src/ \( -name *.c -o -name *.cc \) | xargs clang-tidy -p $(OUT_DIR) -fix
+	@find test/ \( -name *.c -o -name *.cc \) | xargs clang-tidy -p $(OUT_DIR) -fix
 
 .PHONY: check
 check: $(OUT_DIR)/build.ninja
 	@$(NINJA) -C $(OUT_DIR)
 	@echo "Checking..."
-	@find src/ \( -name *.c -o -name *.cc \) -exec clang-check -p $(OUT_DIR) -analyze {} \;
-	@find test/ \( -name *.c -o -name *.cc \) -exec clang-check -p $(OUT_DIR) -analyze {} \;
+	@find src/ \( -name *.c -o -name *.cc \) | xargs clang-check -p $(OUT_DIR) -analyze
+	@find test/ \( -name *.c -o -name *.cc \) | xargs clang-check -p $(OUT_DIR) -analyze
 
 .PHONY: license
 license:
diff --git a/src/api.c b/src/api.c
index 11df107..1d44691 100644
--- a/src/api.c
+++ b/src/api.c
@@ -300,6 +300,14 @@
 		primary_ret =
 			HF_VCPU_RUN_RESPONSE(HF_VCPU_RUN_MESSAGE, 0, size);
 		ret = 0;
+		/*
+		 * clang-tidy isn't able to prove that
+		 * `from->id != HF_PRIMARY_VM_ID` so cover that specific case
+		 * explicitly so as not to hide other possible bugs.
+		 */
+		if (from->id == HF_PRIMARY_VM_ID) {
+			vcpu = 0;
+		}
 		goto out;
 	}
 
@@ -386,7 +394,6 @@
 	/* Return pending messages without blocking. */
 	if (vm->mailbox.state == mailbox_state_received) {
 		vm->mailbox.state = mailbox_state_read;
-		block = false;
 		ret = HF_MAILBOX_RECEIVE_RESPONSE(vm->mailbox.recv_from_id,
 						  vm->mailbox.recv_bytes);
 		goto out;