diff --git a/lib/emscripten/src/env.rs b/lib/emscripten/src/env.rs
index ff5bc6d33..c6887ede0 100644
--- a/lib/emscripten/src/env.rs
+++ b/lib/emscripten/src/env.rs
@@ -191,5 +191,5 @@ pub extern "C" fn _sysconf(name: c_int, _ctx: &mut Ctx) -> c_long {
 pub extern "C" fn ___assert_fail(a: c_int, b: c_int, c: c_int, d: c_int, _ctx: &mut Ctx) {
     debug!("emscripten::___assert_fail {} {} {} {}", a, b, c, d);
     // TODO: Implement like emscripten expects regarding memory/page size
-    unimplemented!()
+    // TODO raise an error
 }
diff --git a/lib/emscripten/src/lib.rs b/lib/emscripten/src/lib.rs
index 54507c4dd..95f51e0f7 100644
--- a/lib/emscripten/src/lib.rs
+++ b/lib/emscripten/src/lib.rs
@@ -2344,6 +2344,30 @@ pub fn generate_emscripten_env(globals: &mut EmscriptenGlobals) -> ImportObject
         },
     );
 
+    env_namespace.insert(
+        "_emscripten_random",
+        Export::Function {
+            func: func!(math, _emscripten_random),
+            ctx: Context::Internal,
+            signature: FuncSig {
+                params: vec![],
+                returns: vec![F64],
+            },
+        },
+    );
+
+    env_namespace.insert(
+        "_gmtime",
+        Export::Function {
+            func: func!(time, _gmtime),
+            ctx: Context::Internal,
+            signature: FuncSig {
+                params: vec![I32],
+                returns: vec![I32],
+            },
+        },
+    );
+
     // mock_external!(env_namespace, _time);
     // mock_external!(env_namespace, _sysconf);
     // mock_external!(env_namespace, _strftime);
@@ -2383,6 +2407,7 @@ pub fn generate_emscripten_env(globals: &mut EmscriptenGlobals) -> ImportObject
     // mock_external!(env_namespace, ___syscall102);
     // mock_external!(env_namespace, ___syscall20);
     mock_external!(env_namespace, _dlerror);
+    mock_external!(env_namespace, _gmtime);
 
     imports.register("env", env_namespace);
     imports.register("asm2wasm", asm_namespace);
diff --git a/lib/emscripten/src/math.rs b/lib/emscripten/src/math.rs
index 33a2ff97a..95f39ce79 100644
--- a/lib/emscripten/src/math.rs
+++ b/lib/emscripten/src/math.rs
@@ -14,12 +14,17 @@ pub extern "C" fn _llvm_log2_f64(value: f64, _ctx: &mut Ctx) -> f64 {
 
 pub extern "C" fn _llvm_log10_f32(value: f64, _ctx: &mut Ctx) -> f64 {
     debug!("emscripten::_llvm_log10_f32");
-    unimplemented!()
+    -1.0
 }
 
 pub extern "C" fn _llvm_log2_f32(value: f64, _ctx: &mut Ctx) -> f64 {
     debug!("emscripten::_llvm_log10_f32");
-    unimplemented!()
+    -1.0
+}
+
+pub extern "C" fn _emscripten_random(_ctx: &mut Ctx) -> f64 {
+    debug!("emscripten::_emscripten_random");
+    -1.0
 }
 
 // emscripten: f64-rem
diff --git a/lib/emscripten/src/time.rs b/lib/emscripten/src/time.rs
index 32bf5f0d9..87f405feb 100644
--- a/lib/emscripten/src/time.rs
+++ b/lib/emscripten/src/time.rs
@@ -109,6 +109,11 @@ pub extern "C" fn _mktime(one: i32, ctx: &mut Ctx) -> i32 {
     -1
 }
 
+pub extern "C" fn _gmtime(one: i32, ctx: &mut Ctx) -> i32 {
+    debug!("emscripten::_gmtime");
+    -1
+}
+
 #[repr(C)]
 struct guest_tm {
     pub tm_sec: c_int,    // 0