diff --git a/src/gallium/auxiliary/tessellator/tessellator.cpp b/src/gallium/auxiliary/tessellator/tessellator.cpp
index c2dc40f571e..952928b060b 100644
--- a/src/gallium/auxiliary/tessellator/tessellator.cpp
+++ b/src/gallium/auxiliary/tessellator/tessellator.cpp
@@ -18,6 +18,7 @@
 */
 
 #include "tessellator.hpp"
+#include "util/macros.h"
 #if defined(_MSC_VER)
 #include <math.h> // ceil
 #else
@@ -2228,6 +2229,8 @@ void CHLSLTessellator::QuadHLSLProcessTessFactors( float tessFactor_Ueq0, float
         case PIPE_TESSELLATOR_REDUCTION_AVERAGE:
             insideTessFactor[U] = (tessFactor_Veq0 + tessFactor_Veq1 + tessFactor_Ueq0 + tessFactor_Ueq1) / 4;
             break;
+        default:
+            unreachable("impossible m_insideTessFactorReduction");
         }
         // Scale inside tessFactor based on user scale factor.
 
@@ -2293,6 +2296,8 @@ void CHLSLTessellator::QuadHLSLProcessTessFactors( float tessFactor_Ueq0, float
             insideTessFactor[U] = (tessFactor_Veq0 + tessFactor_Veq1) / 2;
             insideTessFactor[V] = (tessFactor_Ueq0 + tessFactor_Ueq1) / 2;
             break;
+        default:
+            unreachable("impossible m_insideTessFactorReduction");
         }
         // Scale inside tessFactors based on user scale factor.
 
@@ -2464,6 +2469,8 @@ void CHLSLTessellator::TriHLSLProcessTessFactors( float tessFactor_Ueq0, float t
     case PIPE_TESSELLATOR_REDUCTION_AVERAGE:
         insideTessFactor = (tessFactor_Ueq0 + tessFactor_Veq0 + tessFactor_Weq0) / 3;
         break;
+    default:
+        unreachable("impossible m_insideTessFactorReduction");
     }
 
     // Scale inside TessFactor based on user scale factor.