diff --git a/GoogleSignIn/Sources/GIDEMMSupport.h b/GoogleSignIn/Sources/GIDEMMSupport.h
index f57a6af7..61f445a4 100644
--- a/GoogleSignIn/Sources/GIDEMMSupport.h
+++ b/GoogleSignIn/Sources/GIDEMMSupport.h
@@ -34,12 +34,13 @@ NS_ASSUME_NONNULL_BEGIN
                       completion:(void (^)(NSError *_Nullable))completion;
 
 /// Gets a new set of URL parameters that contains updated EMM-related URL parameters if needed.
-+ (NSDictionary *)updatedEMMParametersWithParameters:(NSDictionary *)parameters;
++ (NSDictionary<NSString *,NSString *> *)updatedEMMParametersWithParameters:
+    (NSDictionary *)parameters;
 
 /// Gets a new set of URL parameters that also contains EMM-related URL parameters if needed.
-+ (NSDictionary *)parametersWithParameters:(NSDictionary *)parameters
-                                emmSupport:(nullable NSString *)emmSupport
-                    isPasscodeInfoRequired:(BOOL)isPasscodeInfoRequired;
++ (NSDictionary<NSString *,NSString *> *)parametersWithParameters:(NSDictionary *)parameters
+                                                       emmSupport:(nullable NSString *)emmSupport
+                                           isPasscodeInfoRequired:(BOOL)isPasscodeInfoRequired;
 
 @end
 
diff --git a/GoogleSignIn/Sources/GIDEMMSupport.m b/GoogleSignIn/Sources/GIDEMMSupport.m
index 0e7b0369..0914d841 100644
--- a/GoogleSignIn/Sources/GIDEMMSupport.m
+++ b/GoogleSignIn/Sources/GIDEMMSupport.m
@@ -84,16 +84,16 @@ + (void)handleTokenFetchEMMError:(nullable NSError *)error
   }
 }
 
-+ (NSDictionary *)updatedEMMParametersWithParameters:(NSDictionary *)parameters {
++ (NSDictionary<NSString *,NSString *> *)updatedEMMParametersWithParameters:
+    (NSDictionary *)parameters {
   return [self parametersWithParameters:parameters
                              emmSupport:parameters[kEMMSupportParameterName]
                  isPasscodeInfoRequired:parameters[kEMMPasscodeInfoParameterName] != nil];
 }
 
-
-+ (NSDictionary *)parametersWithParameters:(NSDictionary *)parameters
-                                emmSupport:(nullable NSString *)emmSupport
-                    isPasscodeInfoRequired:(BOOL)isPasscodeInfoRequired {
++ (NSDictionary<NSString *,NSString *> *)parametersWithParameters:(NSDictionary *)parameters
+                                                       emmSupport:(nullable NSString *)emmSupport
+                                           isPasscodeInfoRequired:(BOOL)isPasscodeInfoRequired {
   if (!emmSupport) {
     return parameters;
   }
@@ -109,7 +109,7 @@ + (NSDictionary *)parametersWithParameters:(NSDictionary *)parameters
   if (isPasscodeInfoRequired) {
     allParameters[kEMMPasscodeInfoParameterName] = [GIDMDMPasscodeState passcodeState].info;
   }
-  return allParameters;
+  return [GIDEMMSupport dictionaryWithStringValuesFromDictionary:allParameters];
 }
 
 #pragma mark - GTMAuthSessionDelegate
@@ -128,6 +128,30 @@ - (void)updateErrorForAuthSession:(GTMAuthSession *)authSession
   }];
 }
 
+#pragma mark - Private Helpers
+
++ (NSDictionary<NSString *, NSString *> *)
+    dictionaryWithStringValuesFromDictionary:(NSDictionary *)originalDictionary {
+  NSMutableDictionary<NSString *, NSString *> *stringifiedDictionary =
+      [NSMutableDictionary dictionaryWithCapacity:originalDictionary.count];
+
+  [originalDictionary enumerateKeysAndObjectsUsingBlock:^(NSString *key, id value, BOOL *stop) {
+    if ([value isKindOfClass:[NSString class]]) {
+      stringifiedDictionary[key] = value;
+        return;
+    }
+    if ([value isKindOfClass:[NSNumber class]]) {
+      if (CFGetTypeID((__bridge CFTypeRef)value) == CFBooleanGetTypeID()) {
+        stringifiedDictionary[key] = [value boolValue] ? @"true" : @"false";
+      } else {
+        stringifiedDictionary[key] = [value stringValue];
+      }
+      return;
+    }
+  }];
+  return stringifiedDictionary;
+}
+
 @end
 
 NS_ASSUME_NONNULL_END
diff --git a/GoogleSignIn/Tests/Unit/GIDEMMSupportTest.m b/GoogleSignIn/Tests/Unit/GIDEMMSupportTest.m
index 990aa733..9aece13b 100644
--- a/GoogleSignIn/Tests/Unit/GIDEMMSupportTest.m
+++ b/GoogleSignIn/Tests/Unit/GIDEMMSupportTest.m
@@ -274,6 +274,86 @@ - (void)testHandleTokenFetchEMMError_errorIsNotEMM {
   [self waitForExpectations:@[ called ] timeout:1];
 }
 
+# pragma mark - String Conversion Tests
+
+- (void)testParametersWithParameters_withAnyNumber_isConvertedToString {
+  NSDictionary *inputParameters = @{ @"number_key": @12345 };
+
+  NSDictionary *stringifiedParameters = [GIDEMMSupport parametersWithParameters:inputParameters
+                                                                     emmSupport:@"1"
+                                                         isPasscodeInfoRequired:NO];
+
+  XCTAssertEqualObjects(stringifiedParameters[@"number_key"], @"12345",
+                        @"The NSNumber should be converted to a string.");
+  XCTAssertTrue([stringifiedParameters[@"number_key"] isKindOfClass:[NSString class]],
+                @"The final value should be of a NSString type.");
+}
+
+- (void)testParametersWithParameters_withNumberOne_isConvertedToString {
+  NSDictionary *inputParameters = @{ @"number_key": @1 };
+
+  NSDictionary *stringifiedParameters = [GIDEMMSupport parametersWithParameters:inputParameters
+                                                                     emmSupport:@"1"
+                                                         isPasscodeInfoRequired:NO];
+
+  XCTAssertEqualObjects(stringifiedParameters[@"number_key"], @"1",
+                        @"The NSNumber should be converted to a string.");
+  XCTAssertTrue([stringifiedParameters[@"number_key"] isKindOfClass:[NSString class]],
+                @"The final value should be of a NSString type.");
+}
+
+- (void)testParametersWithParameters_withNumberZero_isConvertedToString {
+  NSDictionary *inputParameters = @{ @"number_key": @0};
+
+  NSDictionary *stringifiedParameters = [GIDEMMSupport parametersWithParameters:inputParameters
+                                                                     emmSupport:@"1"
+                                                         isPasscodeInfoRequired:NO];
+
+  XCTAssertEqualObjects(stringifiedParameters[@"number_key"], @"0",
+                        @"The NSNumber should be converted to a string.");
+  XCTAssertTrue([stringifiedParameters[@"number_key"] isKindOfClass:[NSString class]],
+                @"The final value should be of a NSString type.");
+}
+
+- (void)testParametersWithParameters_withBooleanYes_isConvertedToTrueString {
+  NSDictionary *inputParameters = @{ @"bool_key": @YES };
+
+  NSDictionary *stringifiedParameters = [GIDEMMSupport parametersWithParameters:inputParameters
+                                                                     emmSupport:@"1"
+                                                         isPasscodeInfoRequired:NO];
+
+  XCTAssertEqualObjects(stringifiedParameters[@"bool_key"], @"true",
+                        @"The boolean YES should be converted to the string 'true'.");
+  XCTAssertTrue([stringifiedParameters[@"bool_key"] isKindOfClass:[NSString class]],
+                @"The final value should be of a NSString type.");
+}
+
+- (void)testParametersWithParameters_withBooleanNo_isConvertedToFalseString {
+  NSDictionary *inputParameters = @{ @"bool_key": @NO };
+
+  NSDictionary *stringifiedParameters = [GIDEMMSupport parametersWithParameters:inputParameters
+                                                                     emmSupport:@"1"
+                                                         isPasscodeInfoRequired:NO];
+
+  XCTAssertEqualObjects(stringifiedParameters[@"bool_key"], @"false",
+                        @"The boolean NO should be converted to the string 'false'.");
+  XCTAssertTrue([stringifiedParameters[@"bool_key"] isKindOfClass:[NSString class]],
+                @"The final value should be of a NSString type.");
+}
+
+- (void)testParametersWithParameters_withString_remainsUnchanged {
+  NSDictionary *inputParameters = @{ @"string_key": @"hello" };
+
+  NSDictionary *stringifiedParameters = [GIDEMMSupport parametersWithParameters:inputParameters
+                                                                     emmSupport:@"1"
+                                                         isPasscodeInfoRequired:NO];
+
+  XCTAssertEqualObjects(stringifiedParameters[@"string_key"], @"hello",
+                        @"The original string value should be preserved.");
+  XCTAssertTrue([stringifiedParameters[@"string_key"] isKindOfClass:[NSString class]],
+                @"The final value should be of a NSString type.");
+}
+
 # pragma mark - Helpers
 
 - (NSString *)systemVersion {