diff --git a/src/xrt/auxiliary/util/u_format.c b/src/xrt/auxiliary/util/u_format.c
index 3b22fc8a6..fd07c3155 100644
--- a/src/xrt/auxiliary/util/u_format.c
+++ b/src/xrt/auxiliary/util/u_format.c
@@ -24,7 +24,9 @@ u_format_str(enum xrt_format f)
 	case XRT_FORMAT_YUV888: return "XRT_FORMAT_YUV888";
 	case XRT_FORMAT_YUV422: return "XRT_FORMAT_YUV422";
 	case XRT_FORMAT_MJPEG: return "XRT_FORMAT_MJPEG";
-	default: assert(!"unsupported format");
+	default:
+		assert(!"unsupported format");
+		return 0;
 	}
 }
 
@@ -44,7 +46,9 @@ u_format_is_blocks(enum xrt_format f)
 	case XRT_FORMAT_MJPEG:
 		// Compressed
 		return false;
-	default: assert(!"unsupported format");
+	default:
+		assert(!"unsupported format");
+		return 0;
 	}
 }
 
@@ -65,7 +69,9 @@ u_format_block_width(enum xrt_format f)
 	case XRT_FORMAT_BITMAP_8X1:
 		// Eight pixels per block.
 		return 8;
-	default: assert(!"unsupported format");
+	default:
+		assert(!"unsupported format");
+		return 0;
 	}
 }
 
@@ -84,7 +90,9 @@ u_format_block_height(enum xrt_format f)
 	case XRT_FORMAT_BITMAP_8X8:
 		// Eight pixels high.
 		return 8;
-	default: assert(!"unsupported format");
+	default:
+		assert(!"unsupported format");
+		return 0;
 	}
 }
 
@@ -105,7 +113,9 @@ u_format_block_size(enum xrt_format f)
 		return 4;
 	case XRT_FORMAT_BITMAP_8X8: // 64 bits.
 		return 8;
-	default: assert(!"unsupported format");
+	default:
+		assert(!"unsupported format");
+		return 0;
 	}
 }