diff --git a/src/type_determiner.cc b/src/type_determiner.cc
index ad6f9c4..3115e7c 100644
--- a/src/type_determiner.cc
+++ b/src/type_determiner.cc
@@ -576,7 +576,7 @@
     return nullptr;
   }
 
-  if (name == "round" || name == "roundeven") {
+  if (name == "round" || name == "roundeven" || name == "trunc") {
     if (params.size() != 1) {
       error_ = "incorrect number of parameters for " + name +
                ". Expected 1 got " + std::to_string(params.size());
@@ -592,7 +592,10 @@
       *id = GLSLstd450Round;
     } else if (name == "roundeven") {
       *id = GLSLstd450RoundEven;
+    } else if (name == "trunc") {
+      *id = GLSLstd450Trunc;
     }
+
     return params[0]->result_type();
   }
 
diff --git a/src/type_determiner_test.cc b/src/type_determiner_test.cc
index bebeae4..f3a2b89 100644
--- a/src/type_determiner_test.cc
+++ b/src/type_determiner_test.cc
@@ -1589,7 +1589,8 @@
                          ImportData_FloatTest,
                          testing::Values(GLSLData{"round", GLSLstd450Round},
                                          GLSLData{"roundeven",
-                                                  GLSLstd450RoundEven}));
+                                                  GLSLstd450RoundEven},
+                                         GLSLData{"trunc", GLSLstd450Trunc}));
 
 }  // namespace
 }  // namespace tint