diff --git a/src/compiler/iroptimizer.js b/src/compiler/iroptimizer.js
index 416f1c3e06..ae7d98e495 100644
--- a/src/compiler/iroptimizer.js
+++ b/src/compiler/iroptimizer.js
@@ -99,6 +99,14 @@ class TypeState {
         });
     }
 
+    /**
+     * @param {TypeState} other
+     * @returns {boolean}
+     */
+    overwrite (other) {
+        return this.mutate(other, varId => other.variables[varId] ?? InputType.ANY);
+    }
+
     /**
      * @param {*} variable A variable codegen object.
      * @param {InputType} type The type to set this variable to
@@ -490,6 +498,8 @@ class IROptimizer {
 
             if (!script || !script.cachedAnalysisEndState) {
                 modified = state.clear() || modified;
+            } else if (script.yields) {
+                modified = state.overwrite(script.cachedAnalysisEndState) || modified;
             } else {
                 modified = state.after(script.cachedAnalysisEndState) || modified;
             }
@@ -578,6 +588,8 @@ class IROptimizer {
 
             if (!script || !script.cachedAnalysisEndState) {
                 modified = state.clear() || modified;
+            } else if (script.yields) {
+                modified = state.overwrite(script.cachedAnalysisEndState) || modified;
             } else {
                 modified = state.after(script.cachedAnalysisEndState) || modified;
             }
diff --git a/test/fixtures/execute/tw-analyze-yields-due-to-direct-recursion.sb3 b/test/fixtures/execute/tw-analyze-yields-due-to-direct-recursion.sb3
new file mode 100644
index 0000000000..136864b417
Binary files /dev/null and b/test/fixtures/execute/tw-analyze-yields-due-to-direct-recursion.sb3 differ
diff --git a/test/fixtures/execute/tw-exit-state-accounts-for-yields-in-procedures.sb3 b/test/fixtures/execute/tw-exit-state-accounts-for-yields-in-procedures.sb3
new file mode 100644
index 0000000000..6d19444963
Binary files /dev/null and b/test/fixtures/execute/tw-exit-state-accounts-for-yields-in-procedures.sb3 differ
diff --git a/test/snapshot/__snapshots__/tw-analyze-yields-due-to-direct-recursion.sb3.tw-snapshot b/test/snapshot/__snapshots__/tw-analyze-yields-due-to-direct-recursion.sb3.tw-snapshot
new file mode 100644
index 0000000000..c19e45f704
--- /dev/null
+++ b/test/snapshot/__snapshots__/tw-analyze-yields-due-to-direct-recursion.sb3.tw-snapshot
@@ -0,0 +1,39 @@
+// TW Snapshot
+// Input SHA-256: 848a4efc16b174b53f0a4b581e6b6d1091ae9eaa916e040c963e360ce3883509
+
+// Sprite1 script
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+const b0 = runtime.getOpcodeFunction("looks_say");
+const b1 = stage.variables["`jEk@4|i[#Fk?(8x)AV.-my variable"];
+const b2 = stage.variables["FpLI$ida6)qR,q~y`1|*"];
+return function* genXYZ () {
+yield* executeInCompatibilityLayer({"MESSAGE":"plan 1",}, b0, false, false, "j", null);
+b1.value = (1 + 2);
+yield* thread.procedures["Znon-warp recursion %s"](2);
+if ((("" + listGet(b2.value, b1.value)).toLowerCase() === "the only thing".toLowerCase())) {
+yield* executeInCompatibilityLayer({"MESSAGE":"pass",}, b0, false, false, "t", null);
+}
+yield* executeInCompatibilityLayer({"MESSAGE":"end",}, b0, false, false, "s", null);
+retire(); return;
+}; })
+
+// Sprite1 Znon-warp recursion %s
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+return function* genXYZ_non_warp_recursion_ (p0) {
+if (compareGreaterThan(p0, 0)) {
+yield;
+yield* thread.procedures["Znon-warp recursion %s"](((+p0 || 0) - 1));
+}
+return "";
+}; })
+
+// Sprite1 script
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+const b0 = stage.variables["`jEk@4|i[#Fk?(8x)AV.-my variable"];
+return function* genXYZ () {
+for (var a0 = 1; a0 >= 0.5; a0--) {
+yield;
+}
+b0.value = "random";
+retire(); return;
+}; })
diff --git a/test/snapshot/__snapshots__/tw-exit-state-accounts-for-yields-in-procedures.sb3.tw-snapshot b/test/snapshot/__snapshots__/tw-exit-state-accounts-for-yields-in-procedures.sb3.tw-snapshot
new file mode 100644
index 0000000000..c8bf63116b
--- /dev/null
+++ b/test/snapshot/__snapshots__/tw-exit-state-accounts-for-yields-in-procedures.sb3.tw-snapshot
@@ -0,0 +1,38 @@
+// TW Snapshot
+// Input SHA-256: 4715c75fe8effcdcdea3ad810949e33a7b6beb3fbd253c1edc2ed4f2bd093df3
+
+// Sprite1 script
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+const b0 = runtime.getOpcodeFunction("looks_say");
+const b1 = stage.variables["`jEk@4|i[#Fk?(8x)AV.-my variable"];
+const b2 = stage.variables["FpLI$ida6)qR,q~y`1|*"];
+return function* genXYZ () {
+yield* executeInCompatibilityLayer({"MESSAGE":"plan 1",}, b0, false, false, "e", null);
+b1.value = (1 + 2);
+yield* thread.procedures["Zsomething that yields"]();
+if ((("" + listGet(b2.value, b1.value)).toLowerCase() === "the only thing".toLowerCase())) {
+yield* executeInCompatibilityLayer({"MESSAGE":"pass",}, b0, false, false, "o", null);
+}
+yield* executeInCompatibilityLayer({"MESSAGE":"end",}, b0, false, false, "n", null);
+retire(); return;
+}; })
+
+// Sprite1 Zsomething that yields
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+return function* genXYZ_something_that_yield () {
+for (var a0 = 2; a0 >= 0.5; a0--) {
+yield;
+}
+return "";
+}; })
+
+// Sprite1 script
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+const b0 = stage.variables["`jEk@4|i[#Fk?(8x)AV.-my variable"];
+return function* genXYZ () {
+for (var a0 = 1; a0 >= 0.5; a0--) {
+yield;
+}
+b0.value = "random";
+retire(); return;
+}; })
diff --git a/test/snapshot/__snapshots__/tw-procedure-return-recursion.sb3.tw-snapshot b/test/snapshot/__snapshots__/tw-procedure-return-recursion.sb3.tw-snapshot
index 6b2bc2a9f6..c242a148a3 100644
--- a/test/snapshot/__snapshots__/tw-procedure-return-recursion.sb3.tw-snapshot
+++ b/test/snapshot/__snapshots__/tw-procedure-return-recursion.sb3.tw-snapshot
@@ -10,7 +10,7 @@ return function* genXYZ () {
 yield* executeInCompatibilityLayer({"MESSAGE":"plan 18",}, b0, false, false, "G", null);
 b1.value = 0;
 b2.value = (yield* thread.procedures["Znon warp recursion should yield %s"](8));
-if ((b1.value === 4)) {
+if (((+b1.value || 0) === 4)) {
 yield* executeInCompatibilityLayer({"MESSAGE":"pass non warp recursion yields",}, b0, false, false, "ao", null);
 }
 b1.value = 0;
@@ -20,7 +20,7 @@ yield* executeInCompatibilityLayer({"MESSAGE":"pass warp recursion does not yiel
 }
 b1.value = 0;
 b2.value = (yield* thread.procedures["Zfib %s"](7));
-if ((b1.value === 20)) {
+if (((+b1.value || 0) === 20)) {
 yield* executeInCompatibilityLayer({"MESSAGE":"pass non warp fib yielded",}, b0, false, false, "au", null);
 }
 yield* thread.procedures["Zrecursing yields between each %s"]("initial");
diff --git a/test/snapshot/__snapshots__/warp-timer/tw-analyze-yields-due-to-direct-recursion.sb3.tw-snapshot b/test/snapshot/__snapshots__/warp-timer/tw-analyze-yields-due-to-direct-recursion.sb3.tw-snapshot
new file mode 100644
index 0000000000..c19e45f704
--- /dev/null
+++ b/test/snapshot/__snapshots__/warp-timer/tw-analyze-yields-due-to-direct-recursion.sb3.tw-snapshot
@@ -0,0 +1,39 @@
+// TW Snapshot
+// Input SHA-256: 848a4efc16b174b53f0a4b581e6b6d1091ae9eaa916e040c963e360ce3883509
+
+// Sprite1 script
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+const b0 = runtime.getOpcodeFunction("looks_say");
+const b1 = stage.variables["`jEk@4|i[#Fk?(8x)AV.-my variable"];
+const b2 = stage.variables["FpLI$ida6)qR,q~y`1|*"];
+return function* genXYZ () {
+yield* executeInCompatibilityLayer({"MESSAGE":"plan 1",}, b0, false, false, "j", null);
+b1.value = (1 + 2);
+yield* thread.procedures["Znon-warp recursion %s"](2);
+if ((("" + listGet(b2.value, b1.value)).toLowerCase() === "the only thing".toLowerCase())) {
+yield* executeInCompatibilityLayer({"MESSAGE":"pass",}, b0, false, false, "t", null);
+}
+yield* executeInCompatibilityLayer({"MESSAGE":"end",}, b0, false, false, "s", null);
+retire(); return;
+}; })
+
+// Sprite1 Znon-warp recursion %s
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+return function* genXYZ_non_warp_recursion_ (p0) {
+if (compareGreaterThan(p0, 0)) {
+yield;
+yield* thread.procedures["Znon-warp recursion %s"](((+p0 || 0) - 1));
+}
+return "";
+}; })
+
+// Sprite1 script
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+const b0 = stage.variables["`jEk@4|i[#Fk?(8x)AV.-my variable"];
+return function* genXYZ () {
+for (var a0 = 1; a0 >= 0.5; a0--) {
+yield;
+}
+b0.value = "random";
+retire(); return;
+}; })
diff --git a/test/snapshot/__snapshots__/warp-timer/tw-exit-state-accounts-for-yields-in-procedures.sb3.tw-snapshot b/test/snapshot/__snapshots__/warp-timer/tw-exit-state-accounts-for-yields-in-procedures.sb3.tw-snapshot
new file mode 100644
index 0000000000..c8bf63116b
--- /dev/null
+++ b/test/snapshot/__snapshots__/warp-timer/tw-exit-state-accounts-for-yields-in-procedures.sb3.tw-snapshot
@@ -0,0 +1,38 @@
+// TW Snapshot
+// Input SHA-256: 4715c75fe8effcdcdea3ad810949e33a7b6beb3fbd253c1edc2ed4f2bd093df3
+
+// Sprite1 script
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+const b0 = runtime.getOpcodeFunction("looks_say");
+const b1 = stage.variables["`jEk@4|i[#Fk?(8x)AV.-my variable"];
+const b2 = stage.variables["FpLI$ida6)qR,q~y`1|*"];
+return function* genXYZ () {
+yield* executeInCompatibilityLayer({"MESSAGE":"plan 1",}, b0, false, false, "e", null);
+b1.value = (1 + 2);
+yield* thread.procedures["Zsomething that yields"]();
+if ((("" + listGet(b2.value, b1.value)).toLowerCase() === "the only thing".toLowerCase())) {
+yield* executeInCompatibilityLayer({"MESSAGE":"pass",}, b0, false, false, "o", null);
+}
+yield* executeInCompatibilityLayer({"MESSAGE":"end",}, b0, false, false, "n", null);
+retire(); return;
+}; })
+
+// Sprite1 Zsomething that yields
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+return function* genXYZ_something_that_yield () {
+for (var a0 = 2; a0 >= 0.5; a0--) {
+yield;
+}
+return "";
+}; })
+
+// Sprite1 script
+(function factoryXYZ(thread) { const target = thread.target; const runtime = target.runtime; const stage = runtime.getTargetForStage();
+const b0 = stage.variables["`jEk@4|i[#Fk?(8x)AV.-my variable"];
+return function* genXYZ () {
+for (var a0 = 1; a0 >= 0.5; a0--) {
+yield;
+}
+b0.value = "random";
+retire(); return;
+}; })
diff --git a/test/snapshot/__snapshots__/warp-timer/tw-procedure-return-recursion.sb3.tw-snapshot b/test/snapshot/__snapshots__/warp-timer/tw-procedure-return-recursion.sb3.tw-snapshot
index 6b2bc2a9f6..c242a148a3 100644
--- a/test/snapshot/__snapshots__/warp-timer/tw-procedure-return-recursion.sb3.tw-snapshot
+++ b/test/snapshot/__snapshots__/warp-timer/tw-procedure-return-recursion.sb3.tw-snapshot
@@ -10,7 +10,7 @@ return function* genXYZ () {
 yield* executeInCompatibilityLayer({"MESSAGE":"plan 18",}, b0, false, false, "G", null);
 b1.value = 0;
 b2.value = (yield* thread.procedures["Znon warp recursion should yield %s"](8));
-if ((b1.value === 4)) {
+if (((+b1.value || 0) === 4)) {
 yield* executeInCompatibilityLayer({"MESSAGE":"pass non warp recursion yields",}, b0, false, false, "ao", null);
 }
 b1.value = 0;
@@ -20,7 +20,7 @@ yield* executeInCompatibilityLayer({"MESSAGE":"pass warp recursion does not yiel
 }
 b1.value = 0;
 b2.value = (yield* thread.procedures["Zfib %s"](7));
-if ((b1.value === 20)) {
+if (((+b1.value || 0) === 20)) {
 yield* executeInCompatibilityLayer({"MESSAGE":"pass non warp fib yielded",}, b0, false, false, "au", null);
 }
 yield* thread.procedures["Zrecursing yields between each %s"]("initial");