diff --git a/src/xrt/auxiliary/vk/vk_compositor_flags.c b/src/xrt/auxiliary/vk/vk_compositor_flags.c
index 72844b443..8c7c286d8 100644
--- a/src/xrt/auxiliary/vk/vk_compositor_flags.c
+++ b/src/xrt/auxiliary/vk/vk_compositor_flags.c
@@ -44,8 +44,8 @@ check_feature(VkFormat format,
 {
 	if ((format_features & flag) == 0) {
 		U_LOG_E("vk_csci_get_image_usage_flags: %s requested but %s not supported for format %s (%08x) (%08x)",
-		        xrt_swapchain_usage_string(usage), vk_format_feature_string(flag), vk_format_string(format),
-		        format_features, flag);
+		        xrt_swapchain_usage_flag_string(usage, false), vk_format_feature_flag_string(flag, false),
+		        vk_format_string(format), format_features, flag);
 		return false;
 	}
 	return true;
diff --git a/src/xrt/auxiliary/vk/vk_helpers.c b/src/xrt/auxiliary/vk/vk_helpers.c
index dd3ff2458..e38c58747 100644
--- a/src/xrt/auxiliary/vk/vk_helpers.c
+++ b/src/xrt/auxiliary/vk/vk_helpers.c
@@ -483,16 +483,23 @@ vk_power_state_string(VkDisplayPowerStateEXT code)
 }
 
 XRT_CHECK_RESULT const char *
-vk_format_feature_string(VkFormatFeatureFlagBits code)
+vk_format_feature_flag_string(VkFormatFeatureFlagBits bits, bool null_on_unknown)
 {
-	switch (code) {
+	switch (bits) {
 		ENUM_TO_STR(VK_FORMAT_FEATURE_SAMPLED_IMAGE_BIT);
 		ENUM_TO_STR(VK_FORMAT_FEATURE_COLOR_ATTACHMENT_BIT);
 		ENUM_TO_STR(VK_FORMAT_FEATURE_DEPTH_STENCIL_ATTACHMENT_BIT);
 		ENUM_TO_STR(VK_FORMAT_FEATURE_TRANSFER_SRC_BIT);
 		ENUM_TO_STR(VK_FORMAT_FEATURE_TRANSFER_DST_BIT);
 		ENUM_TO_STR(VK_FORMAT_R5G6B5_UNORM_PACK16);
-	default: return "UNKNOWN FORMAT FEATURE";
+	default:
+		if (bits == 0) {
+			return "FORMAT FEATURE: NO BITS SET";
+		} else if (bits & (bits - 1)) {
+			return "FORMAT FEATURE: MULTIPLE BITS SET";
+		} else {
+			return null_on_unknown ? NULL : "FORMAT FEATURE: UNKNOWN BIT";
+		}
 	}
 }
 
@@ -592,9 +599,9 @@ vk_surface_transform_flag_string(VkSurfaceTransformFlagBitsKHR bits, bool null_o
 }
 
 XRT_CHECK_RESULT const char *
-xrt_swapchain_usage_string(enum xrt_swapchain_usage_bits code)
+xrt_swapchain_usage_flag_string(enum xrt_swapchain_usage_bits bits, bool null_on_unknown)
 {
-	switch (code) {
+	switch (bits) {
 		ENUM_TO_STR(XRT_SWAPCHAIN_USAGE_COLOR);
 		ENUM_TO_STR(XRT_SWAPCHAIN_USAGE_DEPTH_STENCIL);
 		ENUM_TO_STR(XRT_SWAPCHAIN_USAGE_UNORDERED_ACCESS);
@@ -603,7 +610,14 @@ xrt_swapchain_usage_string(enum xrt_swapchain_usage_bits code)
 		ENUM_TO_STR(XRT_SWAPCHAIN_USAGE_SAMPLED);
 		ENUM_TO_STR(XRT_SWAPCHAIN_USAGE_MUTABLE_FORMAT);
 		ENUM_TO_STR(XRT_SWAPCHAIN_USAGE_INPUT_ATTACHMENT);
-	default: return "UNKNOWN SWAPCHAIN USAGE";
+	default:
+		if (bits == 0) {
+			return "XRT SWAPCHAIN USAGE: NO BITS SET";
+		} else if (bits & (bits - 1)) {
+			return "XRT SWAPCHAIN USAGE: MULTIPLE BITS SET";
+		} else {
+			return null_on_unknown ? NULL : "XRT SWAPCHAIN USAGE: UNKNOWN BIT";
+		}
 	}
 }
 
diff --git a/src/xrt/auxiliary/vk/vk_helpers.h b/src/xrt/auxiliary/vk/vk_helpers.h
index 144970d62..feb8f2f33 100644
--- a/src/xrt/auxiliary/vk/vk_helpers.h
+++ b/src/xrt/auxiliary/vk/vk_helpers.h
@@ -461,8 +461,19 @@ vk_color_space_string(VkColorSpaceKHR code);
 XRT_CHECK_RESULT const char *
 vk_power_state_string(VkDisplayPowerStateEXT code);
 
+
+/*
+ *
+ * Flag bits string functions.
+ *
+ */
+
+/*!
+ * Returns the format feature flag if one valid bit is set,
+ * if multiple bits are set, will return 'MULTIPLE BIT SET'.
+ */
 XRT_CHECK_RESULT const char *
-vk_format_feature_string(VkFormatFeatureFlagBits code);
+vk_format_feature_flag_string(VkFormatFeatureFlagBits bits, bool null_on_unknown);
 
 /*!
  * Returns the image usage flag if one valid bit is set,
@@ -485,8 +496,12 @@ vk_composite_alpha_flag_string(VkCompositeAlphaFlagBitsKHR bits, bool null_on_un
 XRT_CHECK_RESULT const char *
 vk_surface_transform_flag_string(VkSurfaceTransformFlagBitsKHR bits, bool null_on_unknown);
 
+/*!
+ * Returns xrt swapchain_usage flag if one valid bit is set,
+ * if multiple bits are set, will return 'MULTIPLE BIT SET'.
+ */
 XRT_CHECK_RESULT const char *
-xrt_swapchain_usage_string(enum xrt_swapchain_usage_bits code);
+xrt_swapchain_usage_flag_string(enum xrt_swapchain_usage_bits bits, bool null_on_unknown);
 
 
 /*