diff --git a/tests/math_test.cpp b/tests/math_test.cpp
index b4f5b14..ad4654e 100644
--- a/tests/math_test.cpp
+++ b/tests/math_test.cpp
@@ -53,6 +53,8 @@
 #include <limits.h>
 #include <stdint.h>
 
+#include <private/ScopeGuard.h>
+
 float float_subnormal() {
   union {
     float f;
@@ -760,6 +762,10 @@
 }
 
 TEST(math, lrint) {
+  auto guard = create_scope_guard([]() {
+    fesetenv(FE_DFL_ENV);
+  });
+
   fesetround(FE_UPWARD); // lrint/lrintf/lrintl obey the rounding mode.
   ASSERT_EQ(1235, lrint(1234.01));
   ASSERT_EQ(1235, lrintf(1234.01f));
@@ -780,6 +786,10 @@
 }
 
 TEST(math, rint) {
+  auto guard = create_scope_guard([]() {
+    fesetenv(FE_DFL_ENV);
+  });
+
   fesetround(FE_UPWARD); // rint/rintf/rintl obey the rounding mode.
   feclearexcept(FE_ALL_EXCEPT); // rint/rintf/rintl do set the FE_INEXACT flag.
   ASSERT_EQ(1234.0, rint(1234.0));
@@ -806,6 +816,9 @@
 }
 
 TEST(math, nearbyint) {
+  auto guard = create_scope_guard([]() {
+    fesetenv(FE_DFL_ENV);
+  });
   fesetround(FE_UPWARD); // nearbyint/nearbyintf/nearbyintl obey the rounding mode.
   feclearexcept(FE_ALL_EXCEPT); // nearbyint/nearbyintf/nearbyintl don't set the FE_INEXACT flag.
   ASSERT_EQ(1234.0, nearbyint(1234.0));
@@ -832,6 +845,9 @@
 }
 
 TEST(math, lround) {
+  auto guard = create_scope_guard([]() {
+    fesetenv(FE_DFL_ENV);
+  });
   fesetround(FE_UPWARD); // lround ignores the rounding mode.
   ASSERT_EQ(1234, lround(1234.01));
   ASSERT_EQ(1234, lroundf(1234.01f));
@@ -839,6 +855,9 @@
 }
 
 TEST(math, llround) {
+  auto guard = create_scope_guard([]() {
+    fesetenv(FE_DFL_ENV);
+  });
   fesetround(FE_UPWARD); // llround ignores the rounding mode.
   ASSERT_EQ(1234L, llround(1234.01));
   ASSERT_EQ(1234L, llroundf(1234.01f));
@@ -933,6 +952,9 @@
 }
 
 TEST(math, round) {
+  auto guard = create_scope_guard([]() {
+    fesetenv(FE_DFL_ENV);
+  });
   fesetround(FE_TOWARDZERO); // round ignores the rounding mode and always rounds away from zero.
   ASSERT_DOUBLE_EQ(1.0, round(0.5));
   ASSERT_DOUBLE_EQ(-1.0, round(-0.5));
@@ -943,6 +965,9 @@
 }
 
 TEST(math, roundf) {
+  auto guard = create_scope_guard([]() {
+    fesetenv(FE_DFL_ENV);
+  });
   fesetround(FE_TOWARDZERO); // roundf ignores the rounding mode and always rounds away from zero.
   ASSERT_FLOAT_EQ(1.0f, roundf(0.5f));
   ASSERT_FLOAT_EQ(-1.0f, roundf(-0.5f));
@@ -953,6 +978,9 @@
 }
 
 TEST(math, roundl) {
+  auto guard = create_scope_guard([]() {
+    fesetenv(FE_DFL_ENV);
+  });
   fesetround(FE_TOWARDZERO); // roundl ignores the rounding mode and always rounds away from zero.
   ASSERT_DOUBLE_EQ(1.0L, roundl(0.5L));
   ASSERT_DOUBLE_EQ(-1.0L, roundl(-0.5L));
@@ -963,6 +991,9 @@
 }
 
 TEST(math, trunc) {
+  auto guard = create_scope_guard([]() {
+    fesetenv(FE_DFL_ENV);
+  });
   fesetround(FE_UPWARD); // trunc ignores the rounding mode and always rounds toward zero.
   ASSERT_DOUBLE_EQ(1.0, trunc(1.5));
   ASSERT_DOUBLE_EQ(-1.0, trunc(-1.5));
@@ -973,6 +1004,9 @@
 }
 
 TEST(math, truncf) {
+  auto guard = create_scope_guard([]() {
+    fesetenv(FE_DFL_ENV);
+  });
   fesetround(FE_UPWARD); // truncf ignores the rounding mode and always rounds toward zero.
   ASSERT_FLOAT_EQ(1.0f, truncf(1.5f));
   ASSERT_FLOAT_EQ(-1.0f, truncf(-1.5f));
@@ -983,6 +1017,9 @@
 }
 
 TEST(math, truncl) {
+  auto guard = create_scope_guard([]() {
+    fesetenv(FE_DFL_ENV);
+  });
   fesetround(FE_UPWARD); // truncl ignores the rounding mode and always rounds toward zero.
   ASSERT_DOUBLE_EQ(1.0L, truncl(1.5L));
   ASSERT_DOUBLE_EQ(-1.0L, truncl(-1.5L));
diff --git a/tests/string_test.cpp b/tests/string_test.cpp
index ad0040a..6ecbb64 100644
--- a/tests/string_test.cpp
+++ b/tests/string_test.cpp
@@ -196,7 +196,7 @@
   const size_t MAX_LEN;
   Character *ptr, *ptr1, *ptr2;
   size_t n;
-  int len[ITER + 1];
+  size_t len[ITER + 1];
 
  private:
   static size_t alignments[];
@@ -212,7 +212,7 @@
     n = 0;
     len[n++] = 0;
     for (size_t i = 1; i < ITER; ++i) {
-      int l = (int) exp(log((double) MAX_LEN) * i / ITER);
+      size_t l = static_cast<size_t>(exp(log(static_cast<double>(MAX_LEN)) * i / ITER));
       if (l != len[n - 1]) {
         len[n++] = l;
       }
@@ -430,7 +430,7 @@
       }
       state.ptr1[state.len[i] - 1] = '\0';
 
-      int pos = random() % state.MAX_LEN;
+      size_t pos = random() % state.MAX_LEN;
       char* expected;
       if (pos >= state.len[i] - 1) {
         if (seek_char == 0) {
@@ -457,7 +457,7 @@
       state.ptr1[state.len[i] - 1] = '\0';
       state.ptr2[state.len[i] - 1] = '\0';
 
-      int pos = 1 + (random() % (state.MAX_LEN - 1));
+      size_t pos = 1 + (random() % (state.MAX_LEN - 1));
       int actual;
       int expected;
       if (pos >= state.len[i] - 1) {
@@ -540,7 +540,7 @@
       state.ptr2[state.MAX_LEN - 1] = '\0';
       memcpy(state.ptr, state.ptr2, state.MAX_LEN + state.len[i]);
 
-      int pos = random() % state.MAX_LEN;
+      size_t pos = random() % state.MAX_LEN;
       memset(state.ptr1, '\3', pos);
       state.ptr1[pos] = '\0';
       if (pos < state.len[i]) {
@@ -625,7 +625,7 @@
       state.ptr1[state.len[i] - 1] = '\0';
       state.ptr2[state.len[i] - 1] = '\0';
 
-      int pos = 1 + (random() % (state.MAX_LEN - 1));
+      size_t pos = 1 + (random() % (state.MAX_LEN - 1));
       int actual;
       int expected;
       if (pos >= state.len[i] - 1) {
@@ -735,7 +735,7 @@
       }
       state.ptr1[state.len[i] - 1] = '\0';
 
-      int pos = random() % state.MAX_LEN;
+      size_t pos = random() % state.MAX_LEN;
       char* expected;
       if (pos >= state.len[i] - 1) {
         if (seek_char == 0) {
@@ -760,7 +760,7 @@
     for (state.BeginIterations(); state.HasNextIteration(); state.NextIteration()) {
       memset(state.ptr1, ~seek_char, state.len[i]);
 
-      int pos = random() % state.MAX_LEN;
+      size_t pos = random() % state.MAX_LEN;
       char* expected;
       if (pos >= state.len[i]) {
         expected = NULL;
@@ -789,7 +789,7 @@
     for (state.BeginIterations(); state.HasNextIteration(); state.NextIteration()) {
       memset(state.ptr1, ~seek_char, state.len[i]);
 
-      int pos = random() % state.MAX_LEN;
+      size_t pos = random() % state.MAX_LEN;
       char* expected;
       if (pos >= state.len[i]) {
         expected = NULL;