diff --git a/internal/api_test.go b/internal/api_test.go
index 325be5c..9692b29 100644
--- a/internal/api_test.go
+++ b/internal/api_test.go
@@ -235,7 +235,7 @@
 	}
 	f.hang = make(chan int) // only for RunSlowly
 	for _, tc := range testCases {
-		ctx, _ := context.WithTimeout(toContext(c), 100*time.Millisecond)
+		ctx, _ := context.WithTimeout(toContext(c), 300*time.Millisecond)
 		err := Call(ctx, "errors", tc.method, &basepb.VoidProto{}, &basepb.VoidProto{})
 		ce, ok := err.(*CallError)
 		if !ok {
diff --git a/v2/internal/api_test.go b/v2/internal/api_test.go
index 77071db..073e9bf 100644
--- a/v2/internal/api_test.go
+++ b/v2/internal/api_test.go
@@ -212,7 +212,7 @@
 	}
 	f.hang = make(chan int) // only for RunSlowly
 	for _, tc := range testCases {
-		ctx, _ := context.WithTimeout(r.Context(), 100*time.Millisecond)
+		ctx, _ := context.WithTimeout(r.Context(), 300*time.Millisecond)
 		err := Call(ctx, "errors", tc.method, &basepb.VoidProto{}, &basepb.VoidProto{})
 		ce, ok := err.(*CallError)
 		if !ok {