diff --git a/CHANGELOG.md b/CHANGELOG.md
index cf1608c..0e3e3ab 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -29,6 +29,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   x87 stack.
 
 ### Fixed
+- Modulating delaytime in wasm could crash, because delay time was converted to
+  int with i32.trunc_f32_u. Using i32.trunc_f32_s fixed this.
 - When recording notes from VSTI, no track was created for instruments that had
   no notes triggered, resulting in misalignment of the tracks from instruments.
 - 32-bit su_load_gmdls clobbered ebx, even though __stdcall demands it to be not
diff --git a/vm/compiler/templates/wasm/effects.wat b/vm/compiler/templates/wasm/effects.wat
index 82d350d..c492bff 100644
--- a/vm/compiler/templates/wasm/effects.wat
+++ b/vm/compiler/templates/wasm/effects.wat
@@ -313,7 +313,7 @@
                             ))
 {{- end}}
 {{- if .SupportsModulation "delay" "delaytime"}}
-                            (i32.trunc_f32_u (f32.add
+                            (i32.trunc_f32_s (f32.add
                                 (f32.add
                                     (local.get $delayTime)
                                     (f32.mul
@@ -324,7 +324,7 @@
                                 (f32.const 0.5)
                             ))
 {{- else}}
-                            (i32.trunc_f32_u (f32.add (local.get $delayTime) (f32.const 0.5)))
+                            (i32.trunc_f32_s (f32.add (local.get $delayTime) (f32.const 0.5)))
 {{- end}}
 {{- else}}
                             (i32.load16_u