diff --git a/sys/dev/hwpmc/hwpmc_amd.h b/sys/dev/hwpmc/hwpmc_amd.h
index 7f93333cc85..8b0b29f0e98 100644
--- a/sys/dev/hwpmc/hwpmc_amd.h
+++ b/sys/dev/hwpmc/hwpmc_amd.h
@@ -67,7 +67,7 @@
 #define	AMD_PMC_EVENTMASK 	0xF000000FF
 
 #define	AMD_PMC_TO_UNITMASK(x)	(((x) << 8) & AMD_PMC_UNITMASK)
-#define	AMD_PMC_TO_EVENTMASK(x)	(((x) & 0xFF) | (((uint32_t)(x) & 0xF00) << 24))
+#define	AMD_PMC_TO_EVENTMASK(x)	(((x) & 0xFF) | (((uint64_t)(x) & 0xF00) << 24))
 #define	AMD_VALID_BITS		(AMD_PMC_COUNTERMASK | AMD_PMC_INVERT |	\
 	AMD_PMC_ENABLE | AMD_PMC_INT | AMD_PMC_PC | AMD_PMC_EDGE | 	\
 	AMD_PMC_OS | AMD_PMC_USR | AMD_PMC_UNITMASK | AMD_PMC_EVENTMASK)