diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/.gitignore b/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/.gitignore
deleted file mode 100644
index 77d3844f58c..00000000000
--- a/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/.gitignore
+++ /dev/null
@@ -1,2 +0,0 @@
-out
-target
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/Forc.lock b/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/Forc.lock
index 8407bd5c37c..fe603fe62ef 100644
--- a/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/Forc.lock
+++ b/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/Forc.lock
@@ -5,9 +5,4 @@ source = "path+from-root-D73E65B1F4E48513"
 [[package]]
 name = "function_return_type_unification"
 source = "member"
-dependencies = ["std"]
-
-[[package]]
-name = "std"
-source = "path+from-root-D73E65B1F4E48513"
 dependencies = ["core"]
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/Forc.toml b/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/Forc.toml
index 96f4447a531..ebe0edcfda3 100644
--- a/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/Forc.toml
+++ b/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/Forc.toml
@@ -5,4 +5,4 @@ entry = "main.sw"
 license = "Apache-2.0"
 
 [dependencies]
-std = { path = "../../../../reduced_std_libs/sway-lib-std-assert" }
+core = { path = "../../../../../../../sway-lib-core" }
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/src/main.sw b/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/src/main.sw
index 9d5c8d4d08c..761b788e150 100644
--- a/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/src/main.sw
+++ b/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/src/main.sw
@@ -22,8 +22,7 @@ where T: Build,
     T::build()
 }
 
-fn main() -> bool {
-    let _:u32 = produce();
-
-    true
+fn main() -> u32 {
+    let x: u32 = produce();
+    x
 }
\ No newline at end of file
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/test.toml b/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/test.toml
index 1591686ff87..bdd8e5d330a 100644
--- a/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/test.toml
+++ b/test/src/e2e_vm_tests/test_programs/should_pass/language/function_return_type_unification/test.toml
@@ -1,4 +1,4 @@
 category = "run"
-expected_result = { action = "return", value = 1 }
-expected_result_new_encoding = { action = "return_data", value = "01" }
+expected_result = { action = "return", value = 31 }
+expected_result_new_encoding = { action = "return_data", value = "0000001f" }
 validate_abi = false
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/language/type_inference_propagation_of_type_constraints/Forc.lock b/test/src/e2e_vm_tests/test_programs/should_pass/language/type_inference_propagation_of_type_constraints/Forc.lock
new file mode 100644
index 00000000000..c6f5f7c1b5c
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_pass/language/type_inference_propagation_of_type_constraints/Forc.lock
@@ -0,0 +1,8 @@
+[[package]]
+name = "core"
+source = "path+from-root-9D1294DAC07670CA"
+
+[[package]]
+name = "type_inference_propagation_of_type_constraints"
+source = "member"
+dependencies = ["core"]
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/language/type_inference_propagation_of_type_constraints/Forc.toml b/test/src/e2e_vm_tests/test_programs/should_pass/language/type_inference_propagation_of_type_constraints/Forc.toml
new file mode 100644
index 00000000000..c3320e028d2
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_pass/language/type_inference_propagation_of_type_constraints/Forc.toml
@@ -0,0 +1,8 @@
+[project]
+name = "type_inference_propagation_of_type_constraints"
+authors = ["Fuel Labs <contact@fuel.sh>"]
+entry = "main.sw"
+license = "Apache-2.0"
+
+[dependencies]
+core = { path = "../../../../../../../sway-lib-core" }
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/language/type_inference_propagation_of_type_constraints/src/main.sw b/test/src/e2e_vm_tests/test_programs/should_pass/language/type_inference_propagation_of_type_constraints/src/main.sw
new file mode 100644
index 00000000000..4d2413c6d49
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_pass/language/type_inference_propagation_of_type_constraints/src/main.sw
@@ -0,0 +1,64 @@
+// This tests proves that https://github.com/FuelLabs/sway/issues/6379 is fixed.
+
+script;
+
+trait Build {
+    fn build() -> Self;
+}
+
+fn produce<T>() -> T where T: Build {
+    T::build()
+}
+
+impl Build for u8 {
+    fn build() -> Self {
+        7
+    }
+}
+
+impl Build for u32 {
+    fn build() -> Self {
+        31
+    }
+}
+
+impl Build for u64 {
+    fn build() -> Self {
+        63
+    }
+}
+
+fn consume_u8(a: u8) -> u8 {
+    a
+}
+
+fn consume_u32(a: u32) -> u32 {
+    a
+}
+
+fn consume_u64(a: u64) -> u64 {
+    a
+}
+
+fn main() -> (u8, u32, u64) {
+    let a = produce_consume_u8();
+    let b = produce_consume_u32();
+    let c = produce_consume_u64();
+
+    (a, b, c)
+}
+
+fn produce_consume_u8() -> u8 {
+    let x = produce();
+    consume_u8(x)
+}
+
+fn produce_consume_u32() -> u32 {
+    let x = produce();
+    consume_u32(x)
+}
+
+fn produce_consume_u64() -> u64 {
+    let x = produce();
+    consume_u64(x)
+}
\ No newline at end of file
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/language/type_inference_propagation_of_type_constraints/test.toml b/test/src/e2e_vm_tests/test_programs/should_pass/language/type_inference_propagation_of_type_constraints/test.toml
new file mode 100644
index 00000000000..17578590d9b
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_pass/language/type_inference_propagation_of_type_constraints/test.toml
@@ -0,0 +1,4 @@
+category = "run"
+expected_result = { action = "return_data", value = "0700000000000000 000000000000001f 000000000000003f" }
+expected_result_new_encoding = { action = "return_data", value = "07 0000001f 000000000000003f" }
+validate_abi = false